Abstract

Local electric fields play the key role in near-field optical examinations and are especially appealing when exploring heterogeneous or even anisotropic nano-systems. Scattering-type near-field optical microscopy (s-SNOM) is the most commonly used method applied to explore and quantify such confined electric fields at the nanometer length scale: while most works so far did focus on analyzing the z-component oriented perpendicular to the sample surface under p-polarized tip/sample illumination only, recent experimental efforts in s-SNOM report that material resonant excitation might equally allow to probe in-plane electric field components. We thus explore this local vector-field behavior for a simple particle-tip/substrate system by comparing our parametric simulations based on finite element modelling at mid-IR wavelengths, to the standard analytical tip-dipole model. Notably, we analyze all the 4 different combinations for resonant and non-resonant tip and/or sample excitation. Besides the 3-dimensional field confinement under the particle tip present for all scenarios, it is particularly the resonant sample excitations that enable extremely strong field enhancements associated with vector fields pointing along all cartesian coordinates, even without breaking the tip/sample symmetry! In fact, in-plane (s-) resonant sample excitation exceeds the commonly-used p-polarized illumination on non-resonant samples by more than 6 orders of magnitude. Moreover, a variety of different spatial field distributions is found both at and within the sample surface, ranging from electric fields that are oriented strictly perpendicular to the sample surface, to fields that spatially rotate into different directions. Our approach shows that accessing the full vector fields in order to quantify all tensorial properties in nanoscale and modern-type materials lies well within the possibilities and scope of today’s s-SNOM technique.

© 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

1. Introduction

Scattering-type scanning near-field optical microscopy (s-SNOM) provides optical information on the 10-nm length scale over a broad spectral range from visible to far-infrared and THz wavelengths [16]. However, up to date, s-SNOM suffers from its dominant out-of-plane polarization response [79], restricting its application particularly to study biological and nano-materials with polarization-sensitive responses such as molecular vibrations [1012], intermolecular interactions [1315] as well as phonons and bond orientations within a sample [1621]. Utilizing local vector fields at resonant excitation of materials as explored here, may guide future nanoscopic material analysis towards next generation near-field studies including polarization-sensitive 3D probing.

Published SNOM reports mostly focus on quantifying the out-of-plane (z) component of the local electric field [10,22,23]. Only few approaches utilize polarization effects for exciting and probing nanoscopic structures [2429], while sample-resonant excitations so far were not considered. For such non-resonant excitations at visible wavelengths, e.g. tilted tips have been utilized to realize both in-plane and out-of-plane probing of local fields, hence breaking the axial symmetry [30,31]. On the other hand, s-SNOM is frequently applied at mid-infrared (mid-IR) to THz and GHz wavelengths [4,6,20,32] enabling to explore spectral fingerprint regions of molecules [12,33,34], lattice vibrations [35,36], and plasmonic responses in semiconductors [37,38]. In all these cases, the typical length scales of the near-field coupled system under consideration (including tip, tip-sample distance, lateral and vertical field confinement) measure a few nanometer, only, and thus are tiny fractions of the wavelength in use, well justifying the dipole approximations. Impressively, resolution at these wavelengths overcomes the diffraction limit by several orders of magnitude reaching values of up to λ/4600 at THz wavelength [6] and even λ/1.000.000 in the GHz regime [32]. Moreover, applying s-SNOM at those wavelengths enables resonant sample material excitations, resulting in both enhanced signal intensities and improved sensitivity [20,3840], as well as indicating the ability to probe different polarization states by s-SNOM [21,4143]. Nevertheless, a thorough and detailed theoretical discussion is needed in order to understand the corresponding scattering signatures in s-SNOM, and to identify the distribution of local fields for resonant excitation.

In this article, we theoretically investigate the existence of local in-plane vector field components at mid-IR wavelengths by applying 3-dimensional (3D) parametric simulations based on finite element modelling (FEM). We fundamentally analyze the influence of resonant excitation by comparing four cases of near-field coupled systems that represent all combinations of resonant-/non-resonant tip and/or sample excitations. As typical material representatives for non-resonant (metallic) and phonon-based resonant excitation at λ = 15 µm, we chose gold (Au) and strontium titanate (STO), respectively, the latter being a typical material utilized in infrared-optical applications and a widely used substrate for epitaxial thin-film growth. Note that our general findings can directly be applied to many other material systems by spectrally shifting the excitation to the corresponding material resonances, e.g. phononic or plasmonic modes at their corresponding wavelengths.

The four different cases studied here are:

  • (1) Au-tip and Au-sample (non-resonant tip and sample);
  • (2) STO-tip and Au-sample (resonant tip and non-resonant sample);
  • (3) Au-tip and STO-sample (non-resonant tip and resonant sample); and
  • (4) STO-tip and STO-sample (resonant tip and sample).
For these four scenarios (1)-(4), we find fundamental differences in the local fields (see Fig. 1):
  • 1. The field strengths for p-polarized resonant sample excitations are enhanced by as much as a factor 5 as compared to the metallic (non-resonant) case, corresponding to the typical phonon-enhanced s-SNOM behavior [20]. More intriguingly for s-polarized sample-resonant excitations, we find an enhancement by more than 6 orders of magnitude as compared to the non-resonant case (compare Table 1), hence showing significant benefits for s-SNOM examinations.
  • 2. A variety of different spatial field distributions is found for these four cases (see Fig. 1) including strictly orthogonal fields (i.e., electric field components perpendicular to the sample surface) on metallic samples as well as fan-like distributions and spatially rotating fields on resonant samples. The latter two show severe in-plane field components for both p- and s-polarized excitations, respectively, without the need of breaking the tip/sample symmetry by tilting the s-SNOM tip [30,31].
  • 3. Moreover, for sample-resonant excitation, in-plane fields at and within the sample surface are strongly enhanced and can be controlled by both wavelength and the tip-sample distance (details are given in the main text).
  • 4. The spatial field confinement for all four cases is on the order of the tip radius, both along the lateral and vertical axes, clearly reflecting the characteristic near-field localization.
  • 5. Whereas the tip defines the local electric field confinement, it is generally the sample (resonance) that determines superior field enhancement and field orientations that might comprise all vector components.

 

Fig. 1. Comparison of the field distributions at the sample surface for the four configurations of near-field coupled systems (rows) including a spherical tip (radius a = 5 nm) at a tip-sample separation of h0=1 nm and an extended sample for p- and s-polarized excitation (columns). For each case 1 - 4, the vector field distribution is shown along with the extracted values for every field component E||,x, E||,y, and E⊥,z. Notably, the fields on the sample surface have very different characteristics: For p-polarization, the field distribution is dominated by the z-component with a maximum located at x = 0 (underneath the tip). On the other hand, for s-polarization, maxima for E⊥,z are observed at y ≠ 0, while for resonant excitation a dominant in-plane contribution is found at y = 0.

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2. Setup configuration and analytical description

As starting point for our simulations here, we first analytically calculate the near-field enhancement at the scattering probe in close proximity to a sample, based on the dipole model approach. This model is widely used to estimate the scattering cross section in s-SNOM [44] and is adopted here to represent local electric fields. Note, that the dipole model is known to show several limitations, resulting e.g. in inaccuracy of the near-field's decay behavior as well as in restrictions to field orientations perpendicular to the sample surface [45,46]. In order to overcome these limitations, we carry out parametric 3D simulation of the near-field-coupled systems.

 

Fig. 2. Schematic setup of the near-field-coupled tip-sample s-SNOM system, utilized for both analytical calculations and modelling. If not stated otherwise, we assume the following parameters: tip apex radius a = 5 nm, tip-sample distance ${h_0}$=1 nm, illumination with p- or s-polarized light that impinges at an angle of θ = 45°, as well as complex permittivities ${{\varepsilon }_{\textrm{tip}}}$,${\varepsilon _s}$, and ${{\varepsilon }_\textrm{m}}$ for tip, sample, and surrounding medium (air), respectively.

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For both the dipole model and our simulations, the following parameters were used: polarization direction of the incident light (p- or s-polarized light), tip-sample distance h0 and complex material permittivities ɛ, hence including losses. For the simulations, a 3D sphere is defined with perfectly-matched layer (PML) boundary conditions, surrounding the near-field-coupled system. The layout consists of a spherical tip with radius a = 5 nm at a distance h0 to a planar sample surface (see Fig. 2). The sample itself has a size of 150 µm x 150 µm x 100 µm along widths (x,y) and thickness (z), respectively, and is placed in the center of the 3D sphere used for FEM modeling. Note that for this fundamental study of local fields, we assume a symmetric (spherical) tip shape. In experiments, typically elongated tips of different shapes (ellipsoids, pyramids, etc.) are applied, which might be described by a weighting of the different components found here as long as the system is of cylindrical symmetry. However, it shall be noted that additional in-plane field components might be introduced, if this symmetry is broken, e.g. by tilting a non-spherical tip with respect to the sample surface as discussed in [30,31]. A finite element analysis (FEA) method is applied on the coupled system by building accurate mesh for each domain: For instance, the physical domain that includes tip, sample, and surrounding medium (air) is determined with a tetrahedral mesh type with maximum element size of λ/100. Linearly p- or s-polarized light is illuminating the tip-sample system at an incident angle of $\mathrm{\theta }\; = \; 45^\circ $. While for s-polarized light, this geometry results in purely in-plane-(y)-oriented fields, for p-polarized light, this represents the typically mixed polarization state assuming equal components parallel (x) and perpendicular (z) to the sample surface (note that other values for $\mathrm{\theta }$ are expected to principally show the same behavior, however, with different weighting of these two components). In the following p- and s-polarization always refers to the field orientation of the incident light, whereas ‖ and ⊥ as well as x/y and z are used to describe the local in-plane and out-of-plane field components in the sample coordinate system (see Fig. 2). In the simulation, Maxwell equations in frequency domain in the spectral range from 13.5 µm to 16 µm are solved for resonantly excited phonon modes, taking the real and the imaginary part of the material permittivity of tip (${{\varepsilon }_{\textrm{tip}}}$) and sample (${{\varepsilon }_\textrm{s}}$) into account. The proposed schematic setup of the near-field-coupled tip-sample system utilized for both the analytical calculation and FEM modelling is shown in Fig. 2.

Analytically, we apply the dipole model [44] that assumes a purely dipolar excitation of the near-field coupled system. This approximation is particularly well met for infrared wavelengths, since the nanoscopic tip is more than 3 orders of magnitude smaller than the wavelength [47]. In this model, the local vector field on the sample surface underneath the tip is given as:

$${\vec{\textrm{E}}_{\textrm{Local}}} = \frac{{{\mathrm{\alpha }_\textrm{t}}}}{{4\mathrm{\pi }{\textrm{h}^3}}}\left( {\begin{array}{c} {\frac{{\mathrm{\beta } - 1}}{{1 - \frac{{{\mathrm{\alpha }_\textrm{t}}\mathrm{\beta }}}{{32\mathrm{\pi }{\textrm{h}^3}}}}}.{\textrm{E}_{\textrm{x}0}}}\\ {}\\ {\frac{{\mathrm{\beta } - 1}}{{1 - \frac{{{\mathrm{\alpha }_\textrm{t}}\mathrm{\beta }}}{{32\mathrm{\pi }{\textrm{h}^3}}}}}.{\textrm{E}_{\textrm{y}0}}}\\ {}\\ {\frac{{2({\mathrm{\beta } + 1} )}}{{1 - \frac{{{\mathrm{\alpha }_\textrm{t}}\mathrm{\beta }}}{{16\mathrm{\pi }{\textrm{h}^3}}}}}.{\textrm{E}_{\textrm{z}0}}} \end{array}} \right).$$
with $\mathrm{\beta } = \frac{{{{\mathrm{\varepsilon} }_\textrm{s}} - {{\mathrm{\varepsilon} }_\textrm{m}}}}{{{{\mathrm{\varepsilon} }_\textrm{s}} + {{\mathrm{\varepsilon} }_\textrm{m}}}}$ the sample response function, h$= \textrm{a} + {\textrm{h}_0}$ being the distance measured from the center of the tip to the planar sample surface, and ${\vec{\textrm{E}}_0} = \left( {\begin{array}{c} {{\textrm{E}_{\textrm{x}0}}}\\ {\begin{array}{c} {{\textrm{E}_{\textrm{y}0}}}\\ {{\textrm{E}_{\textrm{z}0}}} \end{array}} \end{array}} \right)$ the incident electric field, respectively. Moreover ${\mathrm{\alpha }_\textrm{t}}$ is the tip polarizability with ${\mathrm{\alpha }_\textrm{t}} = 4\mathrm{\pi }{\textrm{a}^3}\frac{{{{\mathrm{\varepsilon} }_{\textrm{tip}}} - {{\mathrm{\varepsilon} }_\textrm{m}}}}{{{{\mathrm{\varepsilon} }_{\textrm{tip}}} + 2{{\mathrm{\varepsilon} }_\textrm{m}}}}$ for the assumed spherical tip shape. We take air as the surrounding medium with ${{\mathrm{\varepsilon} }_\textrm{m}} = 1$, and complex permittivities for both tip (${{\mathrm{\varepsilon} }_{\textrm{tip}}}$) and sample (${{\mathrm{\varepsilon} }_\textrm{s}}$).

The absolute value of the local electric fields are plotted in Fig. 3 as functions of the real part of the tip and the sample permittivities, with imaginary parts kept fixed at 0.1. Strongly enhanced fields underneath the tip are obtained for both perpendicular ($\bot $) and parallel (||) components of the incident field ${\vec{\textrm{E}}_0}$ with respect to the sample surface by setting $ {\vec{\textrm{E}}_{\textrm{0,} \bot }}\textrm{ = }\left( {\begin{array}{c} \textrm{0}\\ {\begin{array}{c} \textrm{0}\\ \textrm{1} \end{array}} \end{array}} \right)$ for $\bot $-field orientation [Fig. 3(a)] and ${\vec{\textrm{E}}_{\textrm{0,||}}}\textrm{ = }\left( {\begin{array}{c} \textrm{1}\\ {\begin{array}{c} \textrm{0}\\ \textrm{0} \end{array}} \end{array}} \right)$ for $\textrm{||}$-field orientation [Fig. 3(b)]. Note that both, fixed imaginary part and strictly $\bot $/$\textrm{||}$ field orientation are in general not reflecting realistic experimental systems, but are applied here to discuss the characteristic behavior of the single components separately. Two branches of enhanced local fields are found for both field components corresponding to sample- and tip-mediated resonances around Re (${{\mathrm{\varepsilon} }_\textrm{s}}) ={-} 1$ and Re (${{\mathrm{\varepsilon} }_{\textrm{tip}}}) ={-} 2$ (Fröhlich resonance) [48], respectively. These branches show a splitting for both permittivities, taking on slightly negative real part values corresponding to the near-field coupling. The strength of this splitting depends on the distance h0 that is set here to 1 nm. Enhancement factors of up to 315 and 52 are found for $\bot $ and || field orientation, respectively, when using resonant excitation of both tip and sample [area 4 marked in Fig. 3(a)]. Whenever only one component, either tip (area 2) or sample (area 3), is excited resonantly, the enhancement factors are reduced to 150 for $\bot $-field components and 15 for ||-field components. Note that for the latter, the enhancement is particularly strong for sample-resonant excitation.

 

Fig. 3. Local electric field strength plotted as a function of the real parts of tip (x-axes) and sample permittivity (y-axes), as calculated via the analytic dipole model within the ± 15 interval: (a) perpendicular (out-of-plane) field component; (b) parallel (in-plane) field orientation. Note that imaginary parts are fixed at 0.1, and the tip with radius a = 5 nm is approached to ho = 1 nm to the sample surface. Notably, two branches of near-field enhancement (brighter colors) are observed for both field components used, corresponding to tip- (area 2) and sample- (area 3) related resonances. Strongest enhancement of the local fields is found for double resonant excitation (area 4) reaching values of up to 315 and 52 for (a) perpendicular ($\bot )$ and (b) parallel (||) field orientation, respectively.

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Even though the dipole model indicates areas of interest for enhanced local fields, it is limited in determining the exact local field distribution near the tip and the sample. Hence, in the following section we apply numerical simulations to model the four near-field-coupled systems, as corresponding to the circled areas 1 - 4 in Fig. 3(a). In the following, we explore the spectral regime around λ=13.5-16.0 μm at which Au shows strongly negative Re(${\mathrm{\varepsilon} })$-values corresponding to non-resonant material excitations in cases 1, 2, and 3, whereas STO is excited resonantly around Re(${\mathrm{\varepsilon} })$ =-1 to -2 within its phononic Reststrahlen band, hence realizing cases 2, 3, and 4 (exact ${\mathrm{\varepsilon} }$ -values are given below).

3. Near-field-coupled system: simulations and results

In order to explore local vector fields beyond the limitations of the analytical dipole model [Eq. (1)], we simulate the four exemplary near-field-coupled systems for all possible combinations of tip and sample being either resonantly or non-resonantly excited (see areas 1 to 4 in Fig. 3). As model materials, we consider STO and Au in the spectral range of 13.5-16 μm [47]. Here, STO is excited within its phononic Reststrahlen band resulting in ${\mathrm{\varepsilon} }$-values from ${{\mathrm{\varepsilon} }_{\textrm{STO,13}.5\; \mathrm{\mu}\textrm{m}}} =- 0\textrm{.17 + i} \cdot 1.35$ to ${{\mathrm{\varepsilon} }_{\textrm{STO},16\; \mathrm{\mu}\textrm{m}}} =- 5.48 +\textrm{i} \cdot 2.31$ [49] covering possible resonant excitation when used as tip or sample material. On the other hand, Au shows a strongly metallic response for this wavelength region with ${{\mathrm{\varepsilon} }_{\textrm{Au,13}.5\; \mathrm{\mu}\textrm{m}}} \cong - 5746 + \textrm{i} \cdot 2340 $ to ${{\mathrm{\varepsilon} }_{\textrm{Au},16\; \mathrm{\mu}\textrm{m}}} \cong - 7511 + \textrm{i} \cdot 3287$ [50], representing a typically non-resonant material for both tip and sample. In the following subsections, the tip with an apex radius equal to a = 5 nm is illuminated with linearly p- or s-polarized incident light at an angle of θ = 45° (see Fig. 2) and the tip-sample distance is determined for h0 = 1 nm if not stated otherwise, for all configurations. Note that here, unlike in the dipole model discussed above, p-polarized incident light results in mixed local excitation with $\bot $ (z) and || (x)-field components, whereas s-polarized incident light corresponds to strict || (y)-excitation.

3.1 Case 1: Au-tip and Au-sample (non-resonant tip and non-resonant sample)

In this configuration, Au is used as the non-resonant material for both tip and sample. The field enhancement in the vicinity of the tip is plotted in Fig. 4. There exists no field that penetrates either tip or sample, exactly fulfilling the electrostatic boundary conditions of a good metal. The local vector field orientations for both p- and s-polarized incident light are shown in Figs. 4(a) and 4(b), respectively, displaying a strict z-oriented field at the sample surface due to the metal’s boundary condition (see Fig. 1 for a detailed view of these fields at the sample surface, including extracted values for Ex, Ey, and Ez). The lobe shape of the field around the tip generally confirms the dipole model concept, however, indicates a slight asymmetry with stronger, more confined fields towards the sample as known from previous works [51].

 

Fig. 4. Local vector field distributions for case 1 when using non-resonant Au for both tip and sample in the mid-IR wavelength regime, plotted for (a) p- and (b) s-polarized incident light. (c,d) display the total electric fields underneath the tip as a function of tip-sample distance h0 (varied from 1 - 5 nm) and wavelength λ (spectral range from 13.5–16 µm), when using (c) p- and (d) s-polarized incident light. A spectrally flat near-field is found that characteristically decays vs. distance h0. Largest field enhancements of 15.4 are found for p-polarized light at h0 =1nm, whereas for s-polarized light, the field at the sample surface is negligibly small (factor of 1 × 10−6). As expected from a good metal, the vector field on the sample surface has z-components, only.

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In Figs. 4(c) and 4(d), the absolute values for field enhancement at the sample surface underneath the tip is displayed as a function of tip-sample distance h0 and wavelength λ for both p- and s-polarizations, respectively, showing the characteristic near-field decay with h0 and a flat spectral response over the full wavelength regime of interest here. The highest enhancement factor reaches 15.4 for p-polarized light at a distance of h0 = 1 nm. For s-polarized incident light, though, the field is more than 6 orders of magnitudes smaller as compared to p-polarization, reaching factors of 2.6 × 10−6 only, one of the reasons, why s-polarization is usually neglected in near-field microscopy.

3.2 Case 2: STO-tip and Au-sample (resonant tip and non-resonant sample)

In the second scenario, we consider the tip to be excited resonantly by choosing STO as the tip material while the sample (Au) remains non-resonantly excited. Experimental realization of such a system includes special tip coatings or nanoparticles attached to non-resonant tips [52]. Compared to the double-non-resonant case discussed above (in section 3.1) the field enhancement for p- and s-polarization as illustrated in Fig. 5, shows several distinct differences:

  • • Firstly, the maximum field enhancement at h0 = 1 nm reaches 2.7- and 156-times larger values compared to case 1, i.e. values up to 41.7 and 0.00041 for p- and s-polarization, respectively.
  • • Secondly, the asymmetry of the dipole-like field lobes is seen to become (a) more pronounced and (b) stronger enhanced towards the sample [see Figs. 5(a) and 5(b)].
  • • Thirdly, a strong wavelength dependent tip resonance is observed in the chosen wavelength interval with highest field enhancements reached for λ = 15 μm. The exact spectral position of this maximum depends on the tip-sample separation as illustrated in Figs. 5(c) and 5(d) (marked by red circles), with the wavelength dramatically shifting by as much as Δλp = 300 nm and Δλs = 100 nm for p- and s-polarization, respectively.

 

Fig. 5. Local vector field distribution for resonant tip (STO) and non-resonant sample (Au), illustrated for (a) p- and (b) s-polarized incident light. (c,d) show the electric field strength at the sample surface underneath the tip as a function of tip-sample distance h0  and wavelength λ for (c) p- and (d) s-polarization. The local field enhancement on the sample surface reaches 41.7 and 0.00041 for p- and s-polarization at h0 =1nm, respectively (maxima marked by red circles for selected h0). The field penetrates the resonant tip with a strongly wavelength dependent behavior. The field inside the metallic sample is exactly zero, forming the boundary condition for strictly z-oriented field components at the sample surface.

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Notably, electric fields clearly penetrate into the dielectric tip, which needs to be fully accounted for when utilizing coated tips. Moreover, when considering resonant tips, the system is expected to be highly sensitive to the tip shape, also introducing geometrical resonances for the small scatterer used here [53]. As for the vector fields on the metallic sample surface, the surface field is fully z-oriented and the field within the sample is zero.

3.3 Case 3: Au-tip and STO-sample (non-resonant tip and resonant sample)

We consider now a near-field-coupled system consisting of a resonantly excited sample (STO) next to a non-resonant Au tip. The local fields deviate clearly from the pure dipolar shape due to a stronger distortion by the sample surface (Fig. 6). The highest fields at the sample surface underneath the tip at h0 = 1 nm for p- and s-polarized incident light, respectively, reach values of 25.9 and 1.74, being 1.7- and 663000-times larger as compared to the fully non-resonant case 1. Notably, here, not only p-polarized light yields strongly localized electric fields, but equally the (often neglected) s-polarized case shows appreciable in-plane field components reaching significant enhancement factors, a fact that is characteristic to any sample-resonant system. Spectrally, compared to the tip-resonant configuration (case 2), the resonance is slightly red-shifted with maximum fields obtained at λ = 15.5 μm for h0 = 1 nm. The spectral positions of these maxima depend strongly on the tip-sample separation h0 [see red circles in Figs. 6(c) and 6(d)], being most distinct for p-polarized light with shifts of Δλp = 1500 nm and Δλs = 200 nm. This lobe-like behavior is well known for sample-resonant excitation of near-field coupled system, both when applying the dipole model or from experimental studies [21,39,43,54]. For the latter, a variety of sample materials has been studied, showing a quantitative dependence of spectral distribution, field strength and distance dependence on the damping and oscillator strength of the corresponding phonon mode [20,21,39,40,55]. However, the qualitative signature of the field distribution is expected to be similar to STO. While the electric field does not penetrate the metallic tip, appreciable field strengths inside the resonant-sample are observed, enabling the examination of buried structures and deducing sub-surface sample properties. Notably, in-plane local vector fields components are distinguishable both at the sample surface and within the sample, particularly in s-polarized configuration. In fact, the in-plane-field reaches much larger values as compared to cases 1 and 2, reaching values of up to 1.74 for s-polarization.

 

Fig. 6. Local vector field distributions for non-resonant tip (Au) and resonant sample (STO), shown for (a) p- and (b) s-polarized incident light, respectively. (c,d) display field plots underneath the tip, as a function of tip-sample distance h0 and wavelength λ for (c) p- and (d) s-polarization (spectral maxima marked by red circles). Field enhancements of up to 25.9 and 1.74 are found for p- and s-polarization, respectively. The local fields penetrate the STO sample and show significant in-plane components both at the sample surface and within the sample, particularly for s-polarized excitation.

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3.4 Case 4: STO-tip and STO-sample (resonant tip and resonant sample)

In this final configuration, we investigate the behavior of a double-resonant system using resonant STO for both tip and sample material. Clearly, the local fields around the tip are strongly distorted and markedly deviate from the dipolar shape, resulting in a highly polarization- and wavelength-sensitive response (see Fig. 7). The local vector field orientation is highly polarization-sensitive and the field enhancement values for h0 = 1 nm reach 79 and 3.4 for p- and s-polarized incident light, respectively, representing the highest numbers for all the 4 configurations investigated here. Note again, that local fields are significantly strong even for s-polarized incident light in this setup. The spectral positions of the field maxima [red circles in Figs. 7(c), 7(d)] are slightly red-shifted compared to the cases of resonant tip or sample discussed above, and show a distance dependent shift of up to Δλp = 100 nm and Δλs = 500 nm, in agreement with the distance-dependent splitting of the two near-field coupled branches shown in Fig. 3(a), area (4). Significant field penetration into the tip is also observed, being less homogeneous as compared to the previous case 2. Moreover, non-zero fields are present in the sample as well, however, being small as compared to the fields that surround the tip and the sample as discussed in the previous cases. In-plane vector fields are present for both polarizations, but being most distinct in the s-polarized configuration. Markedly for this scenario, two confined field maxima at the sample surface are observed with slightly off-centered positions, electric fields that might be utilized to excite e.g. nano-rod-shaped samples.

 

Fig. 7. Local vector field distribution for resonant tip and sample made up of STO, for both (a) p- and (b) s-polarized incident light. (c,d) display the local field underneath the tip as a function of tip-sample distance h0 and wavelength λ, for (c) p- and (d) s-polarization (spectral maxima marked by red circles). This double-resonant configuration enables the strongest local field enhancements of up to 79 and 3.4 for p- and s-polarized excitation, respectively, demonstrating clearly the significance of s-polarized components for resonant excitation.

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4. Comparison and discussion

Comparing the four different setups (see Table 1) of near-field coupled resonant and/or non-resonant tip/sample systems in terms of absolute values and relative changes with reference to the doubly non-resonant case 1 (Au-tip plus Au-sample), we conclude several findings:

  • • Firstly, the highest local field enhancement on the sample surface is obtained for the double-resonant system, reaching factors of 79 and 3.4 corresponding to 5.1-times and 1’300’000-times the double-non-resonant case 1 for p- and s-polarized incident light, respectively.
  • • Secondly, all cases with resonantly excited samples result in strongly enhanced fields for s-polarized excitation reaching values of more than 6 orders of magnitude larger as compared to the non-resonant response. Hence, for sample-resonant systems, s-polarized excitation reaches significant factors for s-SNOM being on the same order of magnitude as compared to the p-polarized non-resonant (metallic) case.
  • • Thirdly, for material-resonant excitation of tip and/or sample, electric fields penetrate the resonant material. Consequently, for resonant tips in the experimental realization, both coating thickness and tip shape become crucial and must be considered. On the other hand, for resonant samples, while signals of thin films below about a 20 nm thickness might reveal substrate contributions, in general probing of sub-surface sample properties and buried structures is enabled.

Tables Icon

Table 1. Comparison of the four configurations of near-field coupled systems at a h0 =1nm tip-sample separation. We calculate here ratios of field enhancements underneath the tip for both p- and s-polarized incident light, taking the non-resonant tip/sample excitation case 1 as the reference (i.e. Ep/Ep,non =1; Es/Es,non-res =1). Particularly for resonant samples (cases 3 and 4), the local fields for s-polarized excitation are strongly enhanced, reaching significant values on the same order of magnitude as for non-resonant p-polarized excitation, but more than 5 orders of magnitude stronger as compared to the non-resonant s-polarized case.

In general, the local fields on the sample surface show non-symmetric but characteristic distributions for the four different setups (see Fig. 1): For non-resonant (metallic) samples, the fields at the sample surface are oriented strictly perpendicular to the interface having a maximum underneath the tip for p-polarized excitation, whereas the comparably small fields for s-polarized incident light are zero underneath the tip. On the other hand, for resonant samples, in-plane components are present at the sample surface for both p- and s-polarized excitation. More specifically, for p-polarization, out-of-plane components are dominant, and underneath the tip (at x = 0), in-plane field contributions of 5.4% and 2.4% of the total fields are observed in the Au-STO [case 3] and STO-STO [case 4] scenario, respectively. Depending on x ≷ 0, the in-plane component has a different sign, resulting in a characteristic fan-like distributions for p-polarized excitation of sample-resonant systems. On the other hand, for all configurations, s-polarized excitation results in field distributions with two maxima at y ≠ 0 with opposite sign in the out-of-plane component. The shapes of the local fields show different characteristics for the different cases: Whereas for non-resonant, metallic samples, all fields are oriented strictly perpendicular to the sample surface with zero fields at the tip position, the field vectors for resonant samples spatially rotate from one maxima to the other, resulting in maxima of in-plane components at y = 0. Consequently, at this position, even purely in-plane-oriented fields can be observed for cases 3 and 4, respectively. Notable, the sample-resonant case 3 includes a constant, positive field offset for the in-plane component, whereas for the double-resonant case 4, the in-plane field changes sign at the position of the total-field maxima at y ≠ 0.

In conclusion of the simulated cases, we find that all vector components at the sample surface are available for resonant excitation of the sample in a near-field coupled system when considering both, p- and s-polarized light. As such, in-plane fields are present both slightly above the sample surface as well as within the sample; they particularly enable the excitation of molecules and nanoscopic specimen at sample surfaces as well as the investigation of sub-surface sample properties and buried structures.

In its qualitative behavior, the simulation results confirm the estimations of the analytical dipole model: We find distinct resonances of the near-field coupled system when either the tip- or sample-material shows slightly negative values for Re(ɛ). On the other hand compared to the simulation, quantitative values in the dipole model as discussed above (see Fig. 3) are always overestimated (by as much as 15-times) due to the assumed constant losses via Im(ɛ). When using realistic material parameters including losses and known corrections to the tip-dipole displacement [56,57], the dipole model matches much better, resulting in slightly overestimated (∼4-times higher) values only. In our simulation, we always consider the wavelength-dependent losses especially in STO. Here, the resonance is found within the materials’ Reststrahlen band and, consequently, the spectral width and losses are defined by the corresponding phonon mode(s). For such phonon-based resonances, typically, narrow resonances of a 1–2 µm spectral width are found accompanied with low losses [20,21,55]. When applying the concept of resonant excitation to other materials, particularly plasmonic resonances, enhanced losses have to be considered. Moreover, for resonant excitation at shorter wavelengths, e.g. in the visible and near-IR regime, the wavelength-to-tip-size ratio is reduced, a fact that significantly provokes multipole excitation and related field distortions [51]. At the mid-IR wavelengths, however, the 5-nm-sized tip is 3000-times smaller than the wavelength in use and the dipole approximation is well met. Also note, that the spatial confinement is on the order of the tip radius and, hence, the localization of the vector fields impressively exceeds the diffraction limit by more than 3 orders of magnitude. When increasing the tip radius slightly at mid-IR wavelengths, basically the same field distribution can be found with a direct scaling of distance dependence and lateral confinement with the tip radius. However, even though accompanied by a loss of resolution, in s-SNOM experiments larger tip radii are often chosen to increase the signal strength due to enhanced scattering efficiencies particularly at long wavelengths [58].

Finally, it shall be noted that, firstly, the present study does not consider scattering of the local fields into the far-field corresponding to the quantity that then is measured in a s-SNOM experiment. In order to describe the re-radiation of the local field into the far field, one needs to take the specific geometry and parameters of the experiment into account that particularly include the tensorial scattering efficiency of the tip as well as effects of antenna-resonances and angular dependence of scattering. In the recent study of McArdle et al. [40], these particular aspects of scattering signature are discussed for resonant excitation of an STO-sample, however, so far neglecting the corresponding effects of polarization. In this paper here, we explicitly focus on the local field distributions in order to fundamentally explore available vector fields and local sample excitations underneath the tip. Besides their utilization in classical s-SNOM, these local sample excitations might be of interest e.g. for local pump-probe configurations as well as for particle-enhanced Raman spectroscopy. Secondly, as shown in Figs. 47(c), 47(d), the spectral position of the resonances and the field strengths as well as the field distributions displayed in Fig. 1, strongly depend on the tip-sample distance h0, offering the possibility to probe local contributions by modulating h0, which might be applied to both in-plane and out-of-plane components as long as a field gradient in z-direction is present. Exploring these effects, however, is beyond the scope of the present paper and will be subject of future studies.

4. Conclusion

3D parametric simulations were carried out for four different configurations of non-resonant and resonant near-field coupled tip and/or sample for the example of mid-IR excitation. The field enhancement underneath the tip was studied in terms of strength, spatial distribution, and vector orientation reaching particularly strong values for material-resonant excitation of the sample and either non-resonant or resonant tip excitation. In these configurations, s-polarized incident light induces a significantly strong field enhancement, that also includes all vector components. Considering the drawback of strong dependences on the tip-shape and penetration through coating layers for resonant tips, we conclude that it is particularly the sample-resonant/tip-non-resonant configuration that is the most suitable option for realizing strongly enhanced local vector fields both at and below the sample surface. Based on these investigations, we envision the utilization of sample-resonant excitations in polarization-sensitive s-SNOM experiments, in order to unlock its high potential for nanoscopic material analysis via enhanced vector fields.

Funding

Würzburg-Dresden Cluster of Excellence - EXC 2137; Bundesministerium für Bildung und Forschung (05K16ODA, 05K16ODC, 05K19ODA, 05K19ODB).

Acknowledgments

The authors thank Lukas Wehmeier for fruitful discussion and Hamed Koochaki Kelardeh for technical support. This project has been funded by the Würzburg-Dresden Cluster of Excellence- EXC 2137 on Complexity and Topology on Quantum Matter (ct.qmat) and by the Bundesministerium für Bildung und Forschung BMBF under Grant Nos. 05K16ODA, 05K16ODC, 05K19ODA, and 05K19ODB.

Disclosures

The authors declare no conflicts of interest.

References

1. F. Zenhausern, Y. Martin, and H. K. Wickramasinghe, “Scanning Interferometric Apertureless Microscopy: Optical Imaging at 10 Angstrom Resolution,” Science 269(5227), 1083–1085 (1995). [CrossRef]  

2. B. Knoll and F. Keilmann, “Scanning microscopy by mid-infrared near-field scattering,” Nature 399(6732), 134–137 (1999). [CrossRef]  

3. R. Hillenbrand, B. Knoll, and F. Keilmann, “Pure optical contrast in scattering-type scanning near-field microscopy,” J. Microsc. 202(1), 77–83 (2001). [CrossRef]  

4. T. Taubner, R. Hillenbrand, and F. Keilmann, “Performance of visible and mid-infrared scattering-type near-field optical microscopes,” J. Microsc. 210(3), 311–314 (2003). [CrossRef]  

5. A. J. Huber, N. Ocelic, and R. Hillenbrand, “Local excitation and interference of surface phonon polaritons studied by near-field infrared microscopy,” J. Microsc. 229(3), 389–395 (2008). [CrossRef]  

6. F. Kuschewski, H.-G. von Ribbeck, J. Döring, S. Winnerl, L. M. Eng, and S. C. Kehr, “Narrow-band near-field nanoscopy in the spectral range from 1.3 to 8.5 THz,” Appl. Phys. Lett. 108(11), 113102 (2016). [CrossRef]  

7. M. I. Stockman, “Nanofocusing of optical energy in tapered plasmonic waveguides,” Phys. Rev. Lett. 93(13), 137404 (2004). [CrossRef]  

8. S. Berweger, J. M. Atkin, R. L. Olmon, and M. B. Raschke, “Light on the tip of a needle: Plasmonic nanofocusing for spectroscopy on the nanoscale,” J. Phys. Chem. Lett. 3(7), 945–952 (2012). [CrossRef]  

9. N. Mauser and A. Hartschuh, “Tip-enhanced near-field optical microscopy,” Chem. Soc. Rev. 43(4), 1248–1262 (2014). [CrossRef]  

10. T. Mino, Y. Saito, H. Yoshida, S. Kawata, and P. Verma, “Molecular orientation analysis of organic thin films by z-polarization Raman microscope,” J. Raman Spectrosc. 43(12), 2029–2034 (2012). [CrossRef]  

11. M. P. Nikiforov, S. C. Kehr, T. Park, P. Milde, U. Zerweck, C. Loppacher, L. M. Eng, M. J. Therien, N. Engheta, and D. Bonnell, “Probing polarization and dielectric function of molecules with higher order harmonics in scattering–near-field scanning optical microscopy,” J. Appl. Phys. 106(11), 114307 (2009). [CrossRef]  

12. M. Brehm, T. Taubner, R. Hillenbrand, and F. Keilmann, “Infrared Spectroscopic Mapping of Single Nanoparticles and Viruses at Nanoscale Resolution,” Nano Lett. 6(7), 1307–1310 (2006). [CrossRef]  

13. J. Stadler, T. Schmid, and R. Zenobi, “Developments in and practical guidelines for tip-enhanced Raman spectroscopy,” Nanoscale 4(6), 1856–1870 (2012). [CrossRef]  

14. T. Mino, Y. Saito, and P. Verma, “Quantitative analysis of polarization-controlled tip-enhanced Raman imaging through the evaluation of the tip dipole,” ACS Nano 8(10), 10187–10195 (2014). [CrossRef]  

15. L. F. Lee, A. Adronov, R. D. Schaller, J. M. J. Fréchet, and R. J. Saykally, “Intermolecular Coupling in Nanometric Domains of Light-Harvesting Dendrimer Films Studied by Photoluminescence Near-Field Scanning Optical Microscopy (PL NSOM) “,” J. Am. Chem. Soc. 125(2), 536–540 (2003). [CrossRef]  

16. S. Berweger and M. B. Raschke, “Polar Phonon Mode Selection. Rules in Tip-Enhanced Raman Scattering,” J. Raman Spectrosc. 40(10), 1413–1419 (2009). [CrossRef]  

17. P. Verma, T. Ichimura, T. Yano, Y. Saito, and S. Kawata, “Nano-imaging through tip-enhanced Raman spectroscopy: Stepping beyond the classical limits,” Laser Photonics Rev. 4(4), 548–561 (2010). [CrossRef]  

18. Y. Saito and P. Verma, “Polarization-controlled Raman microscopy and nanoscopy,” J. Phys. Chem. Lett. 3(10), 1295–1300 (2012). [CrossRef]  

19. M. D. Sonntag, E. A. Pozzi, N. Jiang, M. C. Hersam, and R. P. Van Duyne, “Recent advances in tip-enhanced Raman spectroscopy,” J. Phys. Chem. Lett. 5(18), 3125–3130 (2014). [CrossRef]  

20. R. Hillenbrand, T. Taubner, and F. Keilmann, “Phonon-enhanced light–matter interaction at the nanometre scale,” Nature 418(6894), 159–162 (2002). [CrossRef]  

21. L. Wehmeier, D. Lang, Y. Liu, X. Zhang, S. Winnerl, L. M. Eng, and S. C. Kehr, “Polarization-dependent near-field phonon nanoscopy of oxides: SrTiO3, LiNbO3, and PbZr0.2Ti0.8O3,” Phys. Rev. B 100(3), 035444 (2019). [CrossRef]  

22. R. H. Rickman and P. R. Dunstan, “Enhancement of lattice defect signatures in graphene and ultrathin graphite using tip-enhanced Raman spectroscopy,” J. Raman Spectrosc. 45(1), 15–21 (2014). [CrossRef]  

23. R. Beams, L. G. Cancado, A. Jorio, A. N. Vamivakas, and L. Novotny, “Tip-enhanced Raman mapping of local strain in graphene,” Nanotechnology 26(17), 175702 (2015). [CrossRef]  

24. N. Rotenberg and L. Kuipers, “Mapping nanoscale light fields,” Nat. Photonics 8(12), 919–926 (2014). [CrossRef]  

25. N. Mauser and A. Hartschuh, “Tip-enhanced near-field optical microscopy,” Chem. Soc. Rev. 43(4), 1248–1262 (2014). [CrossRef]  

26. P. Anger, P. Bharadwaj, and L. Novotny, “Enhancement and quenching of single-molecule fluorescence,” Phys. Rev. Lett. 96(11), 113002 (2006). [CrossRef]  

27. A. Ghimire, E. Shafran, and J. M. Gerton, “Using a sharp metal tip to control the polarization and direction of emission from a quantum dot,” Sci. Rep. 4(1), 6456 (2015). [CrossRef]  

28. R. Eckel, V. Walhorn, C. Pelargus, J. Martini, J. Enderlein, T. Nann, D. Anselmetti, and R. Ros, “Fluorescence-emission control of single CdSe nanocrystals using gold-modified AFM tips,” Small 3(1), 44–49 (2007). [CrossRef]  

29. M. Esslinger, J. Dorfmüller, W. Khunsin, R. Vogelgesang, and K. Kern, “Background-free imaging of plasmonic structures with cross-polarized apertureless scanning near-field optical microscopy,” Rev. Sci. Instrum. 83(3), 033704 (2012). [CrossRef]  

30. R. L. Olmon, M. Rang, P. M. Krenz, B. A. Lail, L. V. Saraf, G. D. Boreman, and M. B. Raschke, “Determination of electric-field, magnetic-field, and electric-current distributions of infrared optical antennas: A near-field optical vector network analyser,” Phys. Rev. Lett. 105(16), 167403 (2010). [CrossRef]  

31. K.-D. Park and M. B. Raschke, “Polarization control with plasmonic antenna-tips: A universal approach for optical nano-crystallography and vector-field imaging,” Nano Lett. 18(5), 2912–2917 (2018). [CrossRef]  

32. F. Keilmann, A. J. Huber, and R. Hillenbrand, “Nanoscale Conductivity Contrast by Scattering-Type Near-Field Optical Microscopy in the Visible, Infrared and THz Domains,” J. Infrared, Millimeter, Terahertz Waves 30, 1255–1268 (2009). [CrossRef]  

33. F. Huth, A. Govyadinov, S. Amarie, W. Nuansing, F. Keilmann, and R. Hillenbrand, “Nano-FTIR Absorption Spectroscopy of Molecular Fingerprints at 20 nm Spatial Resolution,” Nano Lett. 12(8), 3973–3978 (2012). [CrossRef]  

34. O. Khatib, H. A. Bechtel, M. C. Martin, M. B. Raschke, and G. Lawrence Carr, “Far infrared synchrotron near-field nanoimaging and nanospectroscopy,” ACS Photonics 5(7), 2773–2779 (2018). [CrossRef]  

35. P. Hermann, B. Kästner, A. Hoehl, V. Kashcheyevs, P. Patoka, G. Ulrich, J. Feikes, M. Ries, T. Tydecks, B. Beckhoff, E. Rühl, and G. Ulm, “Enhancing the sensitivity of nano-FTIR spectroscopy,” Opt. Express 25(14), 16574–16588 (2017). [CrossRef]  

36. A. J. Huber, F. Keilmann, J. Wittborn, J. Aizpurua, and R. Hillenbrand, “Terahertz near-field nanoscopy of mobile carriers in single semiconductor nanodevices,” Nano Lett. 8(11), 3766–3770 (2008). [CrossRef]  

37. A. J. Huber, J. Wittborn, and R. Hillenbrand, “Infrared spectroscopic near-field mapping of single nanotransistors,” Nanotechnology 21(23), 235702 (2010). [CrossRef]  

38. A. J. Huber, A. Ziegler, T. Köck, and R. Hillenbrand, “Infrared nanoscopy of strained semiconductors,” Nat. Nanotechnol. 4(3), 153–157 (2009). [CrossRef]  

39. S. C. Kehr, M. Cebula, O. Mieth, T. Härtling, J. Seidel, S. Grafström, L. M. Eng, S. Winnerl, D. Stehr, and M. Helm, “Anisotropy Contrast in Phonon-Enhanced Apertureless Near-Field Microscopy Using a Free-Electron Laser,” Phys. Rev. Lett. 100(25), 256403 (2008). [CrossRef]  

40. P. McArdle, D. J. Lahneman, A. Biswas, F. Keilmann, and M. M. Qazilbash, “Near-field infrared nanospectroscopy of sur-face phonon-polariton resonances,” Phys. Rev. Res. 2(2), 023272 (2020). [CrossRef]  

41. P. Alonso-González, P. Albella, M. Schnell, J. Chen, F. Huth, A. García-Etxarri, F. Casanova, F. Golmar, L. Arzubiaga, L. E. Hueso, J. Aizpurua, and R. Hillenbrand, “Resolving the electromagnetic mechanism of surface-enhanced light scattering at single hot spots,” Nat. Commun. 3(1), 684 (2012). [CrossRef]  

42. M. Lewin, C. Baeumer, F. Gunkel, A. Schwedt, F. Gaussmann, J. Wueppen, P. Meuffels, B. Jungbluth, J. Mayer, R. Dittmann, R. Waser, and T. Taubner, “Nanospectroscopy of Infrared Phonon Resonance Enables Local Quantification of Electronic Properties in Doped SrTiO3 Ceramics,” Adv. Funct. Mater. 28(42), 1802834 (2018). [CrossRef]  

43. S. C. Kehr, J. Döring, M. Gensch, M. Helm, and L. M. Eng, “FEL-Based Near-Field Infrared to THz Nanoscopy,” Sync. Rad. News 30(4), 31–35 (2017). [CrossRef]  

44. B. Knoll and F. Keilmann, “Enhanced dielectric contrast in scattering-type scanning near-field optical microscopy,” Opt. Commun. 182(4-6), 321–328 (2000). [CrossRef]  

45. A. Cvitkovic, N. Ocelic, and R. Hillenbrand, “Analytical model for quantitative prediction of material contrasts in scattering-type near-field optical microscopy,” Opt. Express 15(14), 8550–8565 (2007). [CrossRef]  

46. A. S. McLeod, P. Kelly, M. D. Goldflam, Z. Gainsforth, A. J. Westphal, G. Dominguez, M. H. Thiemens, M. M. Fogler, and D. N. Basov, “Model for quantitative tip-enhanced spectroscopy and the extraction of nanoscale-resolved optical constants,” Phys. Rev. B 90(8), 085136 (2014). [CrossRef]  

47. P. Hermann, A. Hoehl, P. Patoka, F. Huth, E. Rühl, and G. Ulm, “Near-field imaging and nano-Fourier-transform infrared spectroscopy using broadband synchrotron radiation,” Opt. Express 21(3), 2913–2919 (2013). [CrossRef]  

48. P. Li, X. Yang, T. W. Maß, J. Hanss, M. Lewin, A. K. U. Michel, M. Wuttig, and T. Taubner, “Reversible optical switching of highly confined phonon–polaritons with an ultrathin phase-change material,” Nat. Mater. 15(8), 870–875 (2016). [CrossRef]  

49. J. Petzelt, T. Ostapchuk, I. Gregora, I. Rychetský, S. Hoffmann-Eifert, A. V. Pronin, Y. Yuzyuk, B. P. Gorshunov, S. Kamba, V. Bovtun, J. Pokorný, M. Savinov, V. Porokhonskyy, D. Rafaja, P. Vaněk, A. Almeida, M. R. Chaves, A. A. Volkov, M. Dressel, and R. Waser, “Dielectric, infrared, and Raman response of doped SrTiO3 ceramics: Evidence of polar grain boundaries,” Phys. Rev. B 64(18), 184111 (2001). [CrossRef]  

50. R. L. Olmon, B. Slovick, T. W. Johnson, D. Shelton, S. -H. Oh, G. D. Boreman, and M. B. Raschke, “Optical dielectric function of gold,” Phys. Rev. B 86, 235147 (2012). [CrossRef]  

51. J. Renger, S. Grafström, and L. M. Eng, “Evanescent wave scattering and local electric field enhancement at ellipsoidal silver particles in the vicinity of a glass surface,” J. Opt. Soc. Am. A 21(7), 1362–1367 (2004). [CrossRef]  

52. M. T. Wenzel, T. Härtling, P. Olk, S. C. Kehr, S. Grafström, S. Winnerl, M. Helm, and L. M. Eng, “Gold nanoparticle tips for optical field confinement in infrared scattering near-field optical microscopy,” Opt. Express 16(16), 12302–12312 (2008). [CrossRef]  

53. C. F. Bohren and D. R. Huffman, “Absorption and Scattering of Light by Small Particles,” WILEY-VCH Verlag GmbH & Co. KGaA, DOI:10.1002/9783527618156 (1998).

54. T. Taubner, F. Keilmann, and R. Hillenbrand, “Nanomechanical resonance tuning and phase effects in optical near-field interaction,” Nano Lett. 4(9), 1669–1672 (2004). [CrossRef]  

55. L. Wehmeier, T. Nörenberg, T. V. A. G. de Oliveira, J. M. Klopf, S. Y. Yang, L. W. Martin, R. Ramesh, L. M. Eng, and S. C. Kehr, “Phonon-induced near-field resonances in multiferroic BiFeO3 thin films at infrared and THz wavelengths,” Appl. Phys. Lett. 116(7), 071103 (2020). [CrossRef]  

56. S. Schneider, J. Seidel, S. Grafström, L. M. Eng, S. Winnerl, D. Stehr, and M. Helm, “Impact of optical in-plane anisotropy on near-field phonon polariton spectroscopy,” Appl. Phys. Lett. 90(14), 143101 (2007). [CrossRef]  

57. J. Renger, S. Grafström, L. M. Eng, and R. Hillenbrand, “Resonant light scattering by near-field-induced phonon polaritons,” Phys. Rev. B 71(7), 075410 (2005). [CrossRef]  

58. C. Maissen, S. Chen, E. Nikulina, A. Govyadinov, and R. Hillenbrand, “Probes for Ultrasensitive THz Nanoscopy,” ACS Photonics 6(5), 1279–1288 (2019). [CrossRef]  

References

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  1. F. Zenhausern, Y. Martin, and H. K. Wickramasinghe, “Scanning Interferometric Apertureless Microscopy: Optical Imaging at 10 Angstrom Resolution,” Science 269(5227), 1083–1085 (1995).
    [Crossref]
  2. B. Knoll and F. Keilmann, “Scanning microscopy by mid-infrared near-field scattering,” Nature 399(6732), 134–137 (1999).
    [Crossref]
  3. R. Hillenbrand, B. Knoll, and F. Keilmann, “Pure optical contrast in scattering-type scanning near-field microscopy,” J. Microsc. 202(1), 77–83 (2001).
    [Crossref]
  4. T. Taubner, R. Hillenbrand, and F. Keilmann, “Performance of visible and mid-infrared scattering-type near-field optical microscopes,” J. Microsc. 210(3), 311–314 (2003).
    [Crossref]
  5. A. J. Huber, N. Ocelic, and R. Hillenbrand, “Local excitation and interference of surface phonon polaritons studied by near-field infrared microscopy,” J. Microsc. 229(3), 389–395 (2008).
    [Crossref]
  6. F. Kuschewski, H.-G. von Ribbeck, J. Döring, S. Winnerl, L. M. Eng, and S. C. Kehr, “Narrow-band near-field nanoscopy in the spectral range from 1.3 to 8.5 THz,” Appl. Phys. Lett. 108(11), 113102 (2016).
    [Crossref]
  7. M. I. Stockman, “Nanofocusing of optical energy in tapered plasmonic waveguides,” Phys. Rev. Lett. 93(13), 137404 (2004).
    [Crossref]
  8. S. Berweger, J. M. Atkin, R. L. Olmon, and M. B. Raschke, “Light on the tip of a needle: Plasmonic nanofocusing for spectroscopy on the nanoscale,” J. Phys. Chem. Lett. 3(7), 945–952 (2012).
    [Crossref]
  9. N. Mauser and A. Hartschuh, “Tip-enhanced near-field optical microscopy,” Chem. Soc. Rev. 43(4), 1248–1262 (2014).
    [Crossref]
  10. T. Mino, Y. Saito, H. Yoshida, S. Kawata, and P. Verma, “Molecular orientation analysis of organic thin films by z-polarization Raman microscope,” J. Raman Spectrosc. 43(12), 2029–2034 (2012).
    [Crossref]
  11. M. P. Nikiforov, S. C. Kehr, T. Park, P. Milde, U. Zerweck, C. Loppacher, L. M. Eng, M. J. Therien, N. Engheta, and D. Bonnell, “Probing polarization and dielectric function of molecules with higher order harmonics in scattering–near-field scanning optical microscopy,” J. Appl. Phys. 106(11), 114307 (2009).
    [Crossref]
  12. M. Brehm, T. Taubner, R. Hillenbrand, and F. Keilmann, “Infrared Spectroscopic Mapping of Single Nanoparticles and Viruses at Nanoscale Resolution,” Nano Lett. 6(7), 1307–1310 (2006).
    [Crossref]
  13. J. Stadler, T. Schmid, and R. Zenobi, “Developments in and practical guidelines for tip-enhanced Raman spectroscopy,” Nanoscale 4(6), 1856–1870 (2012).
    [Crossref]
  14. T. Mino, Y. Saito, and P. Verma, “Quantitative analysis of polarization-controlled tip-enhanced Raman imaging through the evaluation of the tip dipole,” ACS Nano 8(10), 10187–10195 (2014).
    [Crossref]
  15. L. F. Lee, A. Adronov, R. D. Schaller, J. M. J. Fréchet, and R. J. Saykally, “Intermolecular Coupling in Nanometric Domains of Light-Harvesting Dendrimer Films Studied by Photoluminescence Near-Field Scanning Optical Microscopy (PL NSOM) “,” J. Am. Chem. Soc. 125(2), 536–540 (2003).
    [Crossref]
  16. S. Berweger and M. B. Raschke, “Polar Phonon Mode Selection. Rules in Tip-Enhanced Raman Scattering,” J. Raman Spectrosc. 40(10), 1413–1419 (2009).
    [Crossref]
  17. P. Verma, T. Ichimura, T. Yano, Y. Saito, and S. Kawata, “Nano-imaging through tip-enhanced Raman spectroscopy: Stepping beyond the classical limits,” Laser Photonics Rev. 4(4), 548–561 (2010).
    [Crossref]
  18. Y. Saito and P. Verma, “Polarization-controlled Raman microscopy and nanoscopy,” J. Phys. Chem. Lett. 3(10), 1295–1300 (2012).
    [Crossref]
  19. M. D. Sonntag, E. A. Pozzi, N. Jiang, M. C. Hersam, and R. P. Van Duyne, “Recent advances in tip-enhanced Raman spectroscopy,” J. Phys. Chem. Lett. 5(18), 3125–3130 (2014).
    [Crossref]
  20. R. Hillenbrand, T. Taubner, and F. Keilmann, “Phonon-enhanced light–matter interaction at the nanometre scale,” Nature 418(6894), 159–162 (2002).
    [Crossref]
  21. L. Wehmeier, D. Lang, Y. Liu, X. Zhang, S. Winnerl, L. M. Eng, and S. C. Kehr, “Polarization-dependent near-field phonon nanoscopy of oxides: SrTiO3, LiNbO3, and PbZr0.2Ti0.8O3,” Phys. Rev. B 100(3), 035444 (2019).
    [Crossref]
  22. R. H. Rickman and P. R. Dunstan, “Enhancement of lattice defect signatures in graphene and ultrathin graphite using tip-enhanced Raman spectroscopy,” J. Raman Spectrosc. 45(1), 15–21 (2014).
    [Crossref]
  23. R. Beams, L. G. Cancado, A. Jorio, A. N. Vamivakas, and L. Novotny, “Tip-enhanced Raman mapping of local strain in graphene,” Nanotechnology 26(17), 175702 (2015).
    [Crossref]
  24. N. Rotenberg and L. Kuipers, “Mapping nanoscale light fields,” Nat. Photonics 8(12), 919–926 (2014).
    [Crossref]
  25. N. Mauser and A. Hartschuh, “Tip-enhanced near-field optical microscopy,” Chem. Soc. Rev. 43(4), 1248–1262 (2014).
    [Crossref]
  26. P. Anger, P. Bharadwaj, and L. Novotny, “Enhancement and quenching of single-molecule fluorescence,” Phys. Rev. Lett. 96(11), 113002 (2006).
    [Crossref]
  27. A. Ghimire, E. Shafran, and J. M. Gerton, “Using a sharp metal tip to control the polarization and direction of emission from a quantum dot,” Sci. Rep. 4(1), 6456 (2015).
    [Crossref]
  28. R. Eckel, V. Walhorn, C. Pelargus, J. Martini, J. Enderlein, T. Nann, D. Anselmetti, and R. Ros, “Fluorescence-emission control of single CdSe nanocrystals using gold-modified AFM tips,” Small 3(1), 44–49 (2007).
    [Crossref]
  29. M. Esslinger, J. Dorfmüller, W. Khunsin, R. Vogelgesang, and K. Kern, “Background-free imaging of plasmonic structures with cross-polarized apertureless scanning near-field optical microscopy,” Rev. Sci. Instrum. 83(3), 033704 (2012).
    [Crossref]
  30. R. L. Olmon, M. Rang, P. M. Krenz, B. A. Lail, L. V. Saraf, G. D. Boreman, and M. B. Raschke, “Determination of electric-field, magnetic-field, and electric-current distributions of infrared optical antennas: A near-field optical vector network analyser,” Phys. Rev. Lett. 105(16), 167403 (2010).
    [Crossref]
  31. K.-D. Park and M. B. Raschke, “Polarization control with plasmonic antenna-tips: A universal approach for optical nano-crystallography and vector-field imaging,” Nano Lett. 18(5), 2912–2917 (2018).
    [Crossref]
  32. F. Keilmann, A. J. Huber, and R. Hillenbrand, “Nanoscale Conductivity Contrast by Scattering-Type Near-Field Optical Microscopy in the Visible, Infrared and THz Domains,” J. Infrared, Millimeter, Terahertz Waves 30, 1255–1268 (2009).
    [Crossref]
  33. F. Huth, A. Govyadinov, S. Amarie, W. Nuansing, F. Keilmann, and R. Hillenbrand, “Nano-FTIR Absorption Spectroscopy of Molecular Fingerprints at 20 nm Spatial Resolution,” Nano Lett. 12(8), 3973–3978 (2012).
    [Crossref]
  34. O. Khatib, H. A. Bechtel, M. C. Martin, M. B. Raschke, and G. Lawrence Carr, “Far infrared synchrotron near-field nanoimaging and nanospectroscopy,” ACS Photonics 5(7), 2773–2779 (2018).
    [Crossref]
  35. P. Hermann, B. Kästner, A. Hoehl, V. Kashcheyevs, P. Patoka, G. Ulrich, J. Feikes, M. Ries, T. Tydecks, B. Beckhoff, E. Rühl, and G. Ulm, “Enhancing the sensitivity of nano-FTIR spectroscopy,” Opt. Express 25(14), 16574–16588 (2017).
    [Crossref]
  36. A. J. Huber, F. Keilmann, J. Wittborn, J. Aizpurua, and R. Hillenbrand, “Terahertz near-field nanoscopy of mobile carriers in single semiconductor nanodevices,” Nano Lett. 8(11), 3766–3770 (2008).
    [Crossref]
  37. A. J. Huber, J. Wittborn, and R. Hillenbrand, “Infrared spectroscopic near-field mapping of single nanotransistors,” Nanotechnology 21(23), 235702 (2010).
    [Crossref]
  38. A. J. Huber, A. Ziegler, T. Köck, and R. Hillenbrand, “Infrared nanoscopy of strained semiconductors,” Nat. Nanotechnol. 4(3), 153–157 (2009).
    [Crossref]
  39. S. C. Kehr, M. Cebula, O. Mieth, T. Härtling, J. Seidel, S. Grafström, L. M. Eng, S. Winnerl, D. Stehr, and M. Helm, “Anisotropy Contrast in Phonon-Enhanced Apertureless Near-Field Microscopy Using a Free-Electron Laser,” Phys. Rev. Lett. 100(25), 256403 (2008).
    [Crossref]
  40. P. McArdle, D. J. Lahneman, A. Biswas, F. Keilmann, and M. M. Qazilbash, “Near-field infrared nanospectroscopy of sur-face phonon-polariton resonances,” Phys. Rev. Res. 2(2), 023272 (2020).
    [Crossref]
  41. P. Alonso-González, P. Albella, M. Schnell, J. Chen, F. Huth, A. García-Etxarri, F. Casanova, F. Golmar, L. Arzubiaga, L. E. Hueso, J. Aizpurua, and R. Hillenbrand, “Resolving the electromagnetic mechanism of surface-enhanced light scattering at single hot spots,” Nat. Commun. 3(1), 684 (2012).
    [Crossref]
  42. M. Lewin, C. Baeumer, F. Gunkel, A. Schwedt, F. Gaussmann, J. Wueppen, P. Meuffels, B. Jungbluth, J. Mayer, R. Dittmann, R. Waser, and T. Taubner, “Nanospectroscopy of Infrared Phonon Resonance Enables Local Quantification of Electronic Properties in Doped SrTiO3 Ceramics,” Adv. Funct. Mater. 28(42), 1802834 (2018).
    [Crossref]
  43. S. C. Kehr, J. Döring, M. Gensch, M. Helm, and L. M. Eng, “FEL-Based Near-Field Infrared to THz Nanoscopy,” Sync. Rad. News 30(4), 31–35 (2017).
    [Crossref]
  44. B. Knoll and F. Keilmann, “Enhanced dielectric contrast in scattering-type scanning near-field optical microscopy,” Opt. Commun. 182(4-6), 321–328 (2000).
    [Crossref]
  45. A. Cvitkovic, N. Ocelic, and R. Hillenbrand, “Analytical model for quantitative prediction of material contrasts in scattering-type near-field optical microscopy,” Opt. Express 15(14), 8550–8565 (2007).
    [Crossref]
  46. A. S. McLeod, P. Kelly, M. D. Goldflam, Z. Gainsforth, A. J. Westphal, G. Dominguez, M. H. Thiemens, M. M. Fogler, and D. N. Basov, “Model for quantitative tip-enhanced spectroscopy and the extraction of nanoscale-resolved optical constants,” Phys. Rev. B 90(8), 085136 (2014).
    [Crossref]
  47. P. Hermann, A. Hoehl, P. Patoka, F. Huth, E. Rühl, and G. Ulm, “Near-field imaging and nano-Fourier-transform infrared spectroscopy using broadband synchrotron radiation,” Opt. Express 21(3), 2913–2919 (2013).
    [Crossref]
  48. P. Li, X. Yang, T. W. Maß, J. Hanss, M. Lewin, A. K. U. Michel, M. Wuttig, and T. Taubner, “Reversible optical switching of highly confined phonon–polaritons with an ultrathin phase-change material,” Nat. Mater. 15(8), 870–875 (2016).
    [Crossref]
  49. J. Petzelt, T. Ostapchuk, I. Gregora, I. Rychetský, S. Hoffmann-Eifert, A. V. Pronin, Y. Yuzyuk, B. P. Gorshunov, S. Kamba, V. Bovtun, J. Pokorný, M. Savinov, V. Porokhonskyy, D. Rafaja, P. Vaněk, A. Almeida, M. R. Chaves, A. A. Volkov, M. Dressel, and R. Waser, “Dielectric, infrared, and Raman response of doped SrTiO3 ceramics: Evidence of polar grain boundaries,” Phys. Rev. B 64(18), 184111 (2001).
    [Crossref]
  50. R. L. Olmon, B. Slovick, T. W. Johnson, D. Shelton, S. -H. Oh, G. D. Boreman, and M. B. Raschke, “Optical dielectric function of gold,” Phys. Rev. B 86, 235147 (2012).
    [Crossref]
  51. J. Renger, S. Grafström, and L. M. Eng, “Evanescent wave scattering and local electric field enhancement at ellipsoidal silver particles in the vicinity of a glass surface,” J. Opt. Soc. Am. A 21(7), 1362–1367 (2004).
    [Crossref]
  52. M. T. Wenzel, T. Härtling, P. Olk, S. C. Kehr, S. Grafström, S. Winnerl, M. Helm, and L. M. Eng, “Gold nanoparticle tips for optical field confinement in infrared scattering near-field optical microscopy,” Opt. Express 16(16), 12302–12312 (2008).
    [Crossref]
  53. C. F. Bohren and D. R. Huffman, “Absorption and Scattering of Light by Small Particles,” WILEY-VCH Verlag GmbH & Co. KGaA, DOI:10.1002/9783527618156 (1998).
  54. T. Taubner, F. Keilmann, and R. Hillenbrand, “Nanomechanical resonance tuning and phase effects in optical near-field interaction,” Nano Lett. 4(9), 1669–1672 (2004).
    [Crossref]
  55. L. Wehmeier, T. Nörenberg, T. V. A. G. de Oliveira, J. M. Klopf, S. Y. Yang, L. W. Martin, R. Ramesh, L. M. Eng, and S. C. Kehr, “Phonon-induced near-field resonances in multiferroic BiFeO3 thin films at infrared and THz wavelengths,” Appl. Phys. Lett. 116(7), 071103 (2020).
    [Crossref]
  56. S. Schneider, J. Seidel, S. Grafström, L. M. Eng, S. Winnerl, D. Stehr, and M. Helm, “Impact of optical in-plane anisotropy on near-field phonon polariton spectroscopy,” Appl. Phys. Lett. 90(14), 143101 (2007).
    [Crossref]
  57. J. Renger, S. Grafström, L. M. Eng, and R. Hillenbrand, “Resonant light scattering by near-field-induced phonon polaritons,” Phys. Rev. B 71(7), 075410 (2005).
    [Crossref]
  58. C. Maissen, S. Chen, E. Nikulina, A. Govyadinov, and R. Hillenbrand, “Probes for Ultrasensitive THz Nanoscopy,” ACS Photonics 6(5), 1279–1288 (2019).
    [Crossref]

2020 (2)

P. McArdle, D. J. Lahneman, A. Biswas, F. Keilmann, and M. M. Qazilbash, “Near-field infrared nanospectroscopy of sur-face phonon-polariton resonances,” Phys. Rev. Res. 2(2), 023272 (2020).
[Crossref]

L. Wehmeier, T. Nörenberg, T. V. A. G. de Oliveira, J. M. Klopf, S. Y. Yang, L. W. Martin, R. Ramesh, L. M. Eng, and S. C. Kehr, “Phonon-induced near-field resonances in multiferroic BiFeO3 thin films at infrared and THz wavelengths,” Appl. Phys. Lett. 116(7), 071103 (2020).
[Crossref]

2019 (2)

C. Maissen, S. Chen, E. Nikulina, A. Govyadinov, and R. Hillenbrand, “Probes for Ultrasensitive THz Nanoscopy,” ACS Photonics 6(5), 1279–1288 (2019).
[Crossref]

L. Wehmeier, D. Lang, Y. Liu, X. Zhang, S. Winnerl, L. M. Eng, and S. C. Kehr, “Polarization-dependent near-field phonon nanoscopy of oxides: SrTiO3, LiNbO3, and PbZr0.2Ti0.8O3,” Phys. Rev. B 100(3), 035444 (2019).
[Crossref]

2018 (3)

K.-D. Park and M. B. Raschke, “Polarization control with plasmonic antenna-tips: A universal approach for optical nano-crystallography and vector-field imaging,” Nano Lett. 18(5), 2912–2917 (2018).
[Crossref]

M. Lewin, C. Baeumer, F. Gunkel, A. Schwedt, F. Gaussmann, J. Wueppen, P. Meuffels, B. Jungbluth, J. Mayer, R. Dittmann, R. Waser, and T. Taubner, “Nanospectroscopy of Infrared Phonon Resonance Enables Local Quantification of Electronic Properties in Doped SrTiO3 Ceramics,” Adv. Funct. Mater. 28(42), 1802834 (2018).
[Crossref]

O. Khatib, H. A. Bechtel, M. C. Martin, M. B. Raschke, and G. Lawrence Carr, “Far infrared synchrotron near-field nanoimaging and nanospectroscopy,” ACS Photonics 5(7), 2773–2779 (2018).
[Crossref]

2017 (2)

2016 (2)

P. Li, X. Yang, T. W. Maß, J. Hanss, M. Lewin, A. K. U. Michel, M. Wuttig, and T. Taubner, “Reversible optical switching of highly confined phonon–polaritons with an ultrathin phase-change material,” Nat. Mater. 15(8), 870–875 (2016).
[Crossref]

F. Kuschewski, H.-G. von Ribbeck, J. Döring, S. Winnerl, L. M. Eng, and S. C. Kehr, “Narrow-band near-field nanoscopy in the spectral range from 1.3 to 8.5 THz,” Appl. Phys. Lett. 108(11), 113102 (2016).
[Crossref]

2015 (2)

A. Ghimire, E. Shafran, and J. M. Gerton, “Using a sharp metal tip to control the polarization and direction of emission from a quantum dot,” Sci. Rep. 4(1), 6456 (2015).
[Crossref]

R. Beams, L. G. Cancado, A. Jorio, A. N. Vamivakas, and L. Novotny, “Tip-enhanced Raman mapping of local strain in graphene,” Nanotechnology 26(17), 175702 (2015).
[Crossref]

2014 (7)

N. Rotenberg and L. Kuipers, “Mapping nanoscale light fields,” Nat. Photonics 8(12), 919–926 (2014).
[Crossref]

N. Mauser and A. Hartschuh, “Tip-enhanced near-field optical microscopy,” Chem. Soc. Rev. 43(4), 1248–1262 (2014).
[Crossref]

M. D. Sonntag, E. A. Pozzi, N. Jiang, M. C. Hersam, and R. P. Van Duyne, “Recent advances in tip-enhanced Raman spectroscopy,” J. Phys. Chem. Lett. 5(18), 3125–3130 (2014).
[Crossref]

R. H. Rickman and P. R. Dunstan, “Enhancement of lattice defect signatures in graphene and ultrathin graphite using tip-enhanced Raman spectroscopy,” J. Raman Spectrosc. 45(1), 15–21 (2014).
[Crossref]

N. Mauser and A. Hartschuh, “Tip-enhanced near-field optical microscopy,” Chem. Soc. Rev. 43(4), 1248–1262 (2014).
[Crossref]

T. Mino, Y. Saito, and P. Verma, “Quantitative analysis of polarization-controlled tip-enhanced Raman imaging through the evaluation of the tip dipole,” ACS Nano 8(10), 10187–10195 (2014).
[Crossref]

A. S. McLeod, P. Kelly, M. D. Goldflam, Z. Gainsforth, A. J. Westphal, G. Dominguez, M. H. Thiemens, M. M. Fogler, and D. N. Basov, “Model for quantitative tip-enhanced spectroscopy and the extraction of nanoscale-resolved optical constants,” Phys. Rev. B 90(8), 085136 (2014).
[Crossref]

2013 (1)

2012 (8)

F. Huth, A. Govyadinov, S. Amarie, W. Nuansing, F. Keilmann, and R. Hillenbrand, “Nano-FTIR Absorption Spectroscopy of Molecular Fingerprints at 20 nm Spatial Resolution,” Nano Lett. 12(8), 3973–3978 (2012).
[Crossref]

R. L. Olmon, B. Slovick, T. W. Johnson, D. Shelton, S. -H. Oh, G. D. Boreman, and M. B. Raschke, “Optical dielectric function of gold,” Phys. Rev. B 86, 235147 (2012).
[Crossref]

P. Alonso-González, P. Albella, M. Schnell, J. Chen, F. Huth, A. García-Etxarri, F. Casanova, F. Golmar, L. Arzubiaga, L. E. Hueso, J. Aizpurua, and R. Hillenbrand, “Resolving the electromagnetic mechanism of surface-enhanced light scattering at single hot spots,” Nat. Commun. 3(1), 684 (2012).
[Crossref]

J. Stadler, T. Schmid, and R. Zenobi, “Developments in and practical guidelines for tip-enhanced Raman spectroscopy,” Nanoscale 4(6), 1856–1870 (2012).
[Crossref]

T. Mino, Y. Saito, H. Yoshida, S. Kawata, and P. Verma, “Molecular orientation analysis of organic thin films by z-polarization Raman microscope,” J. Raman Spectrosc. 43(12), 2029–2034 (2012).
[Crossref]

S. Berweger, J. M. Atkin, R. L. Olmon, and M. B. Raschke, “Light on the tip of a needle: Plasmonic nanofocusing for spectroscopy on the nanoscale,” J. Phys. Chem. Lett. 3(7), 945–952 (2012).
[Crossref]

M. Esslinger, J. Dorfmüller, W. Khunsin, R. Vogelgesang, and K. Kern, “Background-free imaging of plasmonic structures with cross-polarized apertureless scanning near-field optical microscopy,” Rev. Sci. Instrum. 83(3), 033704 (2012).
[Crossref]

Y. Saito and P. Verma, “Polarization-controlled Raman microscopy and nanoscopy,” J. Phys. Chem. Lett. 3(10), 1295–1300 (2012).
[Crossref]

2010 (3)

P. Verma, T. Ichimura, T. Yano, Y. Saito, and S. Kawata, “Nano-imaging through tip-enhanced Raman spectroscopy: Stepping beyond the classical limits,” Laser Photonics Rev. 4(4), 548–561 (2010).
[Crossref]

R. L. Olmon, M. Rang, P. M. Krenz, B. A. Lail, L. V. Saraf, G. D. Boreman, and M. B. Raschke, “Determination of electric-field, magnetic-field, and electric-current distributions of infrared optical antennas: A near-field optical vector network analyser,” Phys. Rev. Lett. 105(16), 167403 (2010).
[Crossref]

A. J. Huber, J. Wittborn, and R. Hillenbrand, “Infrared spectroscopic near-field mapping of single nanotransistors,” Nanotechnology 21(23), 235702 (2010).
[Crossref]

2009 (4)

A. J. Huber, A. Ziegler, T. Köck, and R. Hillenbrand, “Infrared nanoscopy of strained semiconductors,” Nat. Nanotechnol. 4(3), 153–157 (2009).
[Crossref]

F. Keilmann, A. J. Huber, and R. Hillenbrand, “Nanoscale Conductivity Contrast by Scattering-Type Near-Field Optical Microscopy in the Visible, Infrared and THz Domains,” J. Infrared, Millimeter, Terahertz Waves 30, 1255–1268 (2009).
[Crossref]

M. P. Nikiforov, S. C. Kehr, T. Park, P. Milde, U. Zerweck, C. Loppacher, L. M. Eng, M. J. Therien, N. Engheta, and D. Bonnell, “Probing polarization and dielectric function of molecules with higher order harmonics in scattering–near-field scanning optical microscopy,” J. Appl. Phys. 106(11), 114307 (2009).
[Crossref]

S. Berweger and M. B. Raschke, “Polar Phonon Mode Selection. Rules in Tip-Enhanced Raman Scattering,” J. Raman Spectrosc. 40(10), 1413–1419 (2009).
[Crossref]

2008 (4)

A. J. Huber, N. Ocelic, and R. Hillenbrand, “Local excitation and interference of surface phonon polaritons studied by near-field infrared microscopy,” J. Microsc. 229(3), 389–395 (2008).
[Crossref]

S. C. Kehr, M. Cebula, O. Mieth, T. Härtling, J. Seidel, S. Grafström, L. M. Eng, S. Winnerl, D. Stehr, and M. Helm, “Anisotropy Contrast in Phonon-Enhanced Apertureless Near-Field Microscopy Using a Free-Electron Laser,” Phys. Rev. Lett. 100(25), 256403 (2008).
[Crossref]

A. J. Huber, F. Keilmann, J. Wittborn, J. Aizpurua, and R. Hillenbrand, “Terahertz near-field nanoscopy of mobile carriers in single semiconductor nanodevices,” Nano Lett. 8(11), 3766–3770 (2008).
[Crossref]

M. T. Wenzel, T. Härtling, P. Olk, S. C. Kehr, S. Grafström, S. Winnerl, M. Helm, and L. M. Eng, “Gold nanoparticle tips for optical field confinement in infrared scattering near-field optical microscopy,” Opt. Express 16(16), 12302–12312 (2008).
[Crossref]

2007 (3)

S. Schneider, J. Seidel, S. Grafström, L. M. Eng, S. Winnerl, D. Stehr, and M. Helm, “Impact of optical in-plane anisotropy on near-field phonon polariton spectroscopy,” Appl. Phys. Lett. 90(14), 143101 (2007).
[Crossref]

A. Cvitkovic, N. Ocelic, and R. Hillenbrand, “Analytical model for quantitative prediction of material contrasts in scattering-type near-field optical microscopy,” Opt. Express 15(14), 8550–8565 (2007).
[Crossref]

R. Eckel, V. Walhorn, C. Pelargus, J. Martini, J. Enderlein, T. Nann, D. Anselmetti, and R. Ros, “Fluorescence-emission control of single CdSe nanocrystals using gold-modified AFM tips,” Small 3(1), 44–49 (2007).
[Crossref]

2006 (2)

P. Anger, P. Bharadwaj, and L. Novotny, “Enhancement and quenching of single-molecule fluorescence,” Phys. Rev. Lett. 96(11), 113002 (2006).
[Crossref]

M. Brehm, T. Taubner, R. Hillenbrand, and F. Keilmann, “Infrared Spectroscopic Mapping of Single Nanoparticles and Viruses at Nanoscale Resolution,” Nano Lett. 6(7), 1307–1310 (2006).
[Crossref]

2005 (1)

J. Renger, S. Grafström, L. M. Eng, and R. Hillenbrand, “Resonant light scattering by near-field-induced phonon polaritons,” Phys. Rev. B 71(7), 075410 (2005).
[Crossref]

2004 (3)

T. Taubner, F. Keilmann, and R. Hillenbrand, “Nanomechanical resonance tuning and phase effects in optical near-field interaction,” Nano Lett. 4(9), 1669–1672 (2004).
[Crossref]

J. Renger, S. Grafström, and L. M. Eng, “Evanescent wave scattering and local electric field enhancement at ellipsoidal silver particles in the vicinity of a glass surface,” J. Opt. Soc. Am. A 21(7), 1362–1367 (2004).
[Crossref]

M. I. Stockman, “Nanofocusing of optical energy in tapered plasmonic waveguides,” Phys. Rev. Lett. 93(13), 137404 (2004).
[Crossref]

2003 (2)

T. Taubner, R. Hillenbrand, and F. Keilmann, “Performance of visible and mid-infrared scattering-type near-field optical microscopes,” J. Microsc. 210(3), 311–314 (2003).
[Crossref]

L. F. Lee, A. Adronov, R. D. Schaller, J. M. J. Fréchet, and R. J. Saykally, “Intermolecular Coupling in Nanometric Domains of Light-Harvesting Dendrimer Films Studied by Photoluminescence Near-Field Scanning Optical Microscopy (PL NSOM) “,” J. Am. Chem. Soc. 125(2), 536–540 (2003).
[Crossref]

2002 (1)

R. Hillenbrand, T. Taubner, and F. Keilmann, “Phonon-enhanced light–matter interaction at the nanometre scale,” Nature 418(6894), 159–162 (2002).
[Crossref]

2001 (2)

R. Hillenbrand, B. Knoll, and F. Keilmann, “Pure optical contrast in scattering-type scanning near-field microscopy,” J. Microsc. 202(1), 77–83 (2001).
[Crossref]

J. Petzelt, T. Ostapchuk, I. Gregora, I. Rychetský, S. Hoffmann-Eifert, A. V. Pronin, Y. Yuzyuk, B. P. Gorshunov, S. Kamba, V. Bovtun, J. Pokorný, M. Savinov, V. Porokhonskyy, D. Rafaja, P. Vaněk, A. Almeida, M. R. Chaves, A. A. Volkov, M. Dressel, and R. Waser, “Dielectric, infrared, and Raman response of doped SrTiO3 ceramics: Evidence of polar grain boundaries,” Phys. Rev. B 64(18), 184111 (2001).
[Crossref]

2000 (1)

B. Knoll and F. Keilmann, “Enhanced dielectric contrast in scattering-type scanning near-field optical microscopy,” Opt. Commun. 182(4-6), 321–328 (2000).
[Crossref]

1999 (1)

B. Knoll and F. Keilmann, “Scanning microscopy by mid-infrared near-field scattering,” Nature 399(6732), 134–137 (1999).
[Crossref]

1995 (1)

F. Zenhausern, Y. Martin, and H. K. Wickramasinghe, “Scanning Interferometric Apertureless Microscopy: Optical Imaging at 10 Angstrom Resolution,” Science 269(5227), 1083–1085 (1995).
[Crossref]

Adronov, A.

L. F. Lee, A. Adronov, R. D. Schaller, J. M. J. Fréchet, and R. J. Saykally, “Intermolecular Coupling in Nanometric Domains of Light-Harvesting Dendrimer Films Studied by Photoluminescence Near-Field Scanning Optical Microscopy (PL NSOM) “,” J. Am. Chem. Soc. 125(2), 536–540 (2003).
[Crossref]

Aizpurua, J.

P. Alonso-González, P. Albella, M. Schnell, J. Chen, F. Huth, A. García-Etxarri, F. Casanova, F. Golmar, L. Arzubiaga, L. E. Hueso, J. Aizpurua, and R. Hillenbrand, “Resolving the electromagnetic mechanism of surface-enhanced light scattering at single hot spots,” Nat. Commun. 3(1), 684 (2012).
[Crossref]

A. J. Huber, F. Keilmann, J. Wittborn, J. Aizpurua, and R. Hillenbrand, “Terahertz near-field nanoscopy of mobile carriers in single semiconductor nanodevices,” Nano Lett. 8(11), 3766–3770 (2008).
[Crossref]

Albella, P.

P. Alonso-González, P. Albella, M. Schnell, J. Chen, F. Huth, A. García-Etxarri, F. Casanova, F. Golmar, L. Arzubiaga, L. E. Hueso, J. Aizpurua, and R. Hillenbrand, “Resolving the electromagnetic mechanism of surface-enhanced light scattering at single hot spots,” Nat. Commun. 3(1), 684 (2012).
[Crossref]

Almeida, A.

J. Petzelt, T. Ostapchuk, I. Gregora, I. Rychetský, S. Hoffmann-Eifert, A. V. Pronin, Y. Yuzyuk, B. P. Gorshunov, S. Kamba, V. Bovtun, J. Pokorný, M. Savinov, V. Porokhonskyy, D. Rafaja, P. Vaněk, A. Almeida, M. R. Chaves, A. A. Volkov, M. Dressel, and R. Waser, “Dielectric, infrared, and Raman response of doped SrTiO3 ceramics: Evidence of polar grain boundaries,” Phys. Rev. B 64(18), 184111 (2001).
[Crossref]

Alonso-González, P.

P. Alonso-González, P. Albella, M. Schnell, J. Chen, F. Huth, A. García-Etxarri, F. Casanova, F. Golmar, L. Arzubiaga, L. E. Hueso, J. Aizpurua, and R. Hillenbrand, “Resolving the electromagnetic mechanism of surface-enhanced light scattering at single hot spots,” Nat. Commun. 3(1), 684 (2012).
[Crossref]

Amarie, S.

F. Huth, A. Govyadinov, S. Amarie, W. Nuansing, F. Keilmann, and R. Hillenbrand, “Nano-FTIR Absorption Spectroscopy of Molecular Fingerprints at 20 nm Spatial Resolution,” Nano Lett. 12(8), 3973–3978 (2012).
[Crossref]

Anger, P.

P. Anger, P. Bharadwaj, and L. Novotny, “Enhancement and quenching of single-molecule fluorescence,” Phys. Rev. Lett. 96(11), 113002 (2006).
[Crossref]

Anselmetti, D.

R. Eckel, V. Walhorn, C. Pelargus, J. Martini, J. Enderlein, T. Nann, D. Anselmetti, and R. Ros, “Fluorescence-emission control of single CdSe nanocrystals using gold-modified AFM tips,” Small 3(1), 44–49 (2007).
[Crossref]

Arzubiaga, L.

P. Alonso-González, P. Albella, M. Schnell, J. Chen, F. Huth, A. García-Etxarri, F. Casanova, F. Golmar, L. Arzubiaga, L. E. Hueso, J. Aizpurua, and R. Hillenbrand, “Resolving the electromagnetic mechanism of surface-enhanced light scattering at single hot spots,” Nat. Commun. 3(1), 684 (2012).
[Crossref]

Atkin, J. M.

S. Berweger, J. M. Atkin, R. L. Olmon, and M. B. Raschke, “Light on the tip of a needle: Plasmonic nanofocusing for spectroscopy on the nanoscale,” J. Phys. Chem. Lett. 3(7), 945–952 (2012).
[Crossref]

Baeumer, C.

M. Lewin, C. Baeumer, F. Gunkel, A. Schwedt, F. Gaussmann, J. Wueppen, P. Meuffels, B. Jungbluth, J. Mayer, R. Dittmann, R. Waser, and T. Taubner, “Nanospectroscopy of Infrared Phonon Resonance Enables Local Quantification of Electronic Properties in Doped SrTiO3 Ceramics,” Adv. Funct. Mater. 28(42), 1802834 (2018).
[Crossref]

Basov, D. N.

A. S. McLeod, P. Kelly, M. D. Goldflam, Z. Gainsforth, A. J. Westphal, G. Dominguez, M. H. Thiemens, M. M. Fogler, and D. N. Basov, “Model for quantitative tip-enhanced spectroscopy and the extraction of nanoscale-resolved optical constants,” Phys. Rev. B 90(8), 085136 (2014).
[Crossref]

Beams, R.

R. Beams, L. G. Cancado, A. Jorio, A. N. Vamivakas, and L. Novotny, “Tip-enhanced Raman mapping of local strain in graphene,” Nanotechnology 26(17), 175702 (2015).
[Crossref]

Bechtel, H. A.

O. Khatib, H. A. Bechtel, M. C. Martin, M. B. Raschke, and G. Lawrence Carr, “Far infrared synchrotron near-field nanoimaging and nanospectroscopy,” ACS Photonics 5(7), 2773–2779 (2018).
[Crossref]

Beckhoff, B.

Berweger, S.

S. Berweger, J. M. Atkin, R. L. Olmon, and M. B. Raschke, “Light on the tip of a needle: Plasmonic nanofocusing for spectroscopy on the nanoscale,” J. Phys. Chem. Lett. 3(7), 945–952 (2012).
[Crossref]

S. Berweger and M. B. Raschke, “Polar Phonon Mode Selection. Rules in Tip-Enhanced Raman Scattering,” J. Raman Spectrosc. 40(10), 1413–1419 (2009).
[Crossref]

Bharadwaj, P.

P. Anger, P. Bharadwaj, and L. Novotny, “Enhancement and quenching of single-molecule fluorescence,” Phys. Rev. Lett. 96(11), 113002 (2006).
[Crossref]

Biswas, A.

P. McArdle, D. J. Lahneman, A. Biswas, F. Keilmann, and M. M. Qazilbash, “Near-field infrared nanospectroscopy of sur-face phonon-polariton resonances,” Phys. Rev. Res. 2(2), 023272 (2020).
[Crossref]

Bohren, C. F.

C. F. Bohren and D. R. Huffman, “Absorption and Scattering of Light by Small Particles,” WILEY-VCH Verlag GmbH & Co. KGaA, DOI:10.1002/9783527618156 (1998).

Bonnell, D.

M. P. Nikiforov, S. C. Kehr, T. Park, P. Milde, U. Zerweck, C. Loppacher, L. M. Eng, M. J. Therien, N. Engheta, and D. Bonnell, “Probing polarization and dielectric function of molecules with higher order harmonics in scattering–near-field scanning optical microscopy,” J. Appl. Phys. 106(11), 114307 (2009).
[Crossref]

Boreman, G. D.

R. L. Olmon, B. Slovick, T. W. Johnson, D. Shelton, S. -H. Oh, G. D. Boreman, and M. B. Raschke, “Optical dielectric function of gold,” Phys. Rev. B 86, 235147 (2012).
[Crossref]

R. L. Olmon, M. Rang, P. M. Krenz, B. A. Lail, L. V. Saraf, G. D. Boreman, and M. B. Raschke, “Determination of electric-field, magnetic-field, and electric-current distributions of infrared optical antennas: A near-field optical vector network analyser,” Phys. Rev. Lett. 105(16), 167403 (2010).
[Crossref]

Bovtun, V.

J. Petzelt, T. Ostapchuk, I. Gregora, I. Rychetský, S. Hoffmann-Eifert, A. V. Pronin, Y. Yuzyuk, B. P. Gorshunov, S. Kamba, V. Bovtun, J. Pokorný, M. Savinov, V. Porokhonskyy, D. Rafaja, P. Vaněk, A. Almeida, M. R. Chaves, A. A. Volkov, M. Dressel, and R. Waser, “Dielectric, infrared, and Raman response of doped SrTiO3 ceramics: Evidence of polar grain boundaries,” Phys. Rev. B 64(18), 184111 (2001).
[Crossref]

Brehm, M.

M. Brehm, T. Taubner, R. Hillenbrand, and F. Keilmann, “Infrared Spectroscopic Mapping of Single Nanoparticles and Viruses at Nanoscale Resolution,” Nano Lett. 6(7), 1307–1310 (2006).
[Crossref]

Cancado, L. G.

R. Beams, L. G. Cancado, A. Jorio, A. N. Vamivakas, and L. Novotny, “Tip-enhanced Raman mapping of local strain in graphene,” Nanotechnology 26(17), 175702 (2015).
[Crossref]

Casanova, F.

P. Alonso-González, P. Albella, M. Schnell, J. Chen, F. Huth, A. García-Etxarri, F. Casanova, F. Golmar, L. Arzubiaga, L. E. Hueso, J. Aizpurua, and R. Hillenbrand, “Resolving the electromagnetic mechanism of surface-enhanced light scattering at single hot spots,” Nat. Commun. 3(1), 684 (2012).
[Crossref]

Cebula, M.

S. C. Kehr, M. Cebula, O. Mieth, T. Härtling, J. Seidel, S. Grafström, L. M. Eng, S. Winnerl, D. Stehr, and M. Helm, “Anisotropy Contrast in Phonon-Enhanced Apertureless Near-Field Microscopy Using a Free-Electron Laser,” Phys. Rev. Lett. 100(25), 256403 (2008).
[Crossref]

Chaves, M. R.

J. Petzelt, T. Ostapchuk, I. Gregora, I. Rychetský, S. Hoffmann-Eifert, A. V. Pronin, Y. Yuzyuk, B. P. Gorshunov, S. Kamba, V. Bovtun, J. Pokorný, M. Savinov, V. Porokhonskyy, D. Rafaja, P. Vaněk, A. Almeida, M. R. Chaves, A. A. Volkov, M. Dressel, and R. Waser, “Dielectric, infrared, and Raman response of doped SrTiO3 ceramics: Evidence of polar grain boundaries,” Phys. Rev. B 64(18), 184111 (2001).
[Crossref]

Chen, J.

P. Alonso-González, P. Albella, M. Schnell, J. Chen, F. Huth, A. García-Etxarri, F. Casanova, F. Golmar, L. Arzubiaga, L. E. Hueso, J. Aizpurua, and R. Hillenbrand, “Resolving the electromagnetic mechanism of surface-enhanced light scattering at single hot spots,” Nat. Commun. 3(1), 684 (2012).
[Crossref]

Chen, S.

C. Maissen, S. Chen, E. Nikulina, A. Govyadinov, and R. Hillenbrand, “Probes for Ultrasensitive THz Nanoscopy,” ACS Photonics 6(5), 1279–1288 (2019).
[Crossref]

Cvitkovic, A.

de Oliveira, T. V. A. G.

L. Wehmeier, T. Nörenberg, T. V. A. G. de Oliveira, J. M. Klopf, S. Y. Yang, L. W. Martin, R. Ramesh, L. M. Eng, and S. C. Kehr, “Phonon-induced near-field resonances in multiferroic BiFeO3 thin films at infrared and THz wavelengths,” Appl. Phys. Lett. 116(7), 071103 (2020).
[Crossref]

Dittmann, R.

M. Lewin, C. Baeumer, F. Gunkel, A. Schwedt, F. Gaussmann, J. Wueppen, P. Meuffels, B. Jungbluth, J. Mayer, R. Dittmann, R. Waser, and T. Taubner, “Nanospectroscopy of Infrared Phonon Resonance Enables Local Quantification of Electronic Properties in Doped SrTiO3 Ceramics,” Adv. Funct. Mater. 28(42), 1802834 (2018).
[Crossref]

Dominguez, G.

A. S. McLeod, P. Kelly, M. D. Goldflam, Z. Gainsforth, A. J. Westphal, G. Dominguez, M. H. Thiemens, M. M. Fogler, and D. N. Basov, “Model for quantitative tip-enhanced spectroscopy and the extraction of nanoscale-resolved optical constants,” Phys. Rev. B 90(8), 085136 (2014).
[Crossref]

Dorfmüller, J.

M. Esslinger, J. Dorfmüller, W. Khunsin, R. Vogelgesang, and K. Kern, “Background-free imaging of plasmonic structures with cross-polarized apertureless scanning near-field optical microscopy,” Rev. Sci. Instrum. 83(3), 033704 (2012).
[Crossref]

Döring, J.

S. C. Kehr, J. Döring, M. Gensch, M. Helm, and L. M. Eng, “FEL-Based Near-Field Infrared to THz Nanoscopy,” Sync. Rad. News 30(4), 31–35 (2017).
[Crossref]

F. Kuschewski, H.-G. von Ribbeck, J. Döring, S. Winnerl, L. M. Eng, and S. C. Kehr, “Narrow-band near-field nanoscopy in the spectral range from 1.3 to 8.5 THz,” Appl. Phys. Lett. 108(11), 113102 (2016).
[Crossref]

Dressel, M.

J. Petzelt, T. Ostapchuk, I. Gregora, I. Rychetský, S. Hoffmann-Eifert, A. V. Pronin, Y. Yuzyuk, B. P. Gorshunov, S. Kamba, V. Bovtun, J. Pokorný, M. Savinov, V. Porokhonskyy, D. Rafaja, P. Vaněk, A. Almeida, M. R. Chaves, A. A. Volkov, M. Dressel, and R. Waser, “Dielectric, infrared, and Raman response of doped SrTiO3 ceramics: Evidence of polar grain boundaries,” Phys. Rev. B 64(18), 184111 (2001).
[Crossref]

Dunstan, P. R.

R. H. Rickman and P. R. Dunstan, “Enhancement of lattice defect signatures in graphene and ultrathin graphite using tip-enhanced Raman spectroscopy,” J. Raman Spectrosc. 45(1), 15–21 (2014).
[Crossref]

Eckel, R.

R. Eckel, V. Walhorn, C. Pelargus, J. Martini, J. Enderlein, T. Nann, D. Anselmetti, and R. Ros, “Fluorescence-emission control of single CdSe nanocrystals using gold-modified AFM tips,” Small 3(1), 44–49 (2007).
[Crossref]

Enderlein, J.

R. Eckel, V. Walhorn, C. Pelargus, J. Martini, J. Enderlein, T. Nann, D. Anselmetti, and R. Ros, “Fluorescence-emission control of single CdSe nanocrystals using gold-modified AFM tips,” Small 3(1), 44–49 (2007).
[Crossref]

Eng, L. M.

L. Wehmeier, T. Nörenberg, T. V. A. G. de Oliveira, J. M. Klopf, S. Y. Yang, L. W. Martin, R. Ramesh, L. M. Eng, and S. C. Kehr, “Phonon-induced near-field resonances in multiferroic BiFeO3 thin films at infrared and THz wavelengths,” Appl. Phys. Lett. 116(7), 071103 (2020).
[Crossref]

L. Wehmeier, D. Lang, Y. Liu, X. Zhang, S. Winnerl, L. M. Eng, and S. C. Kehr, “Polarization-dependent near-field phonon nanoscopy of oxides: SrTiO3, LiNbO3, and PbZr0.2Ti0.8O3,” Phys. Rev. B 100(3), 035444 (2019).
[Crossref]

S. C. Kehr, J. Döring, M. Gensch, M. Helm, and L. M. Eng, “FEL-Based Near-Field Infrared to THz Nanoscopy,” Sync. Rad. News 30(4), 31–35 (2017).
[Crossref]

F. Kuschewski, H.-G. von Ribbeck, J. Döring, S. Winnerl, L. M. Eng, and S. C. Kehr, “Narrow-band near-field nanoscopy in the spectral range from 1.3 to 8.5 THz,” Appl. Phys. Lett. 108(11), 113102 (2016).
[Crossref]

M. P. Nikiforov, S. C. Kehr, T. Park, P. Milde, U. Zerweck, C. Loppacher, L. M. Eng, M. J. Therien, N. Engheta, and D. Bonnell, “Probing polarization and dielectric function of molecules with higher order harmonics in scattering–near-field scanning optical microscopy,” J. Appl. Phys. 106(11), 114307 (2009).
[Crossref]

S. C. Kehr, M. Cebula, O. Mieth, T. Härtling, J. Seidel, S. Grafström, L. M. Eng, S. Winnerl, D. Stehr, and M. Helm, “Anisotropy Contrast in Phonon-Enhanced Apertureless Near-Field Microscopy Using a Free-Electron Laser,” Phys. Rev. Lett. 100(25), 256403 (2008).
[Crossref]

M. T. Wenzel, T. Härtling, P. Olk, S. C. Kehr, S. Grafström, S. Winnerl, M. Helm, and L. M. Eng, “Gold nanoparticle tips for optical field confinement in infrared scattering near-field optical microscopy,” Opt. Express 16(16), 12302–12312 (2008).
[Crossref]

S. Schneider, J. Seidel, S. Grafström, L. M. Eng, S. Winnerl, D. Stehr, and M. Helm, “Impact of optical in-plane anisotropy on near-field phonon polariton spectroscopy,” Appl. Phys. Lett. 90(14), 143101 (2007).
[Crossref]

J. Renger, S. Grafström, L. M. Eng, and R. Hillenbrand, “Resonant light scattering by near-field-induced phonon polaritons,” Phys. Rev. B 71(7), 075410 (2005).
[Crossref]

J. Renger, S. Grafström, and L. M. Eng, “Evanescent wave scattering and local electric field enhancement at ellipsoidal silver particles in the vicinity of a glass surface,” J. Opt. Soc. Am. A 21(7), 1362–1367 (2004).
[Crossref]

Engheta, N.

M. P. Nikiforov, S. C. Kehr, T. Park, P. Milde, U. Zerweck, C. Loppacher, L. M. Eng, M. J. Therien, N. Engheta, and D. Bonnell, “Probing polarization and dielectric function of molecules with higher order harmonics in scattering–near-field scanning optical microscopy,” J. Appl. Phys. 106(11), 114307 (2009).
[Crossref]

Esslinger, M.

M. Esslinger, J. Dorfmüller, W. Khunsin, R. Vogelgesang, and K. Kern, “Background-free imaging of plasmonic structures with cross-polarized apertureless scanning near-field optical microscopy,” Rev. Sci. Instrum. 83(3), 033704 (2012).
[Crossref]

Feikes, J.

Fogler, M. M.

A. S. McLeod, P. Kelly, M. D. Goldflam, Z. Gainsforth, A. J. Westphal, G. Dominguez, M. H. Thiemens, M. M. Fogler, and D. N. Basov, “Model for quantitative tip-enhanced spectroscopy and the extraction of nanoscale-resolved optical constants,” Phys. Rev. B 90(8), 085136 (2014).
[Crossref]

Fréchet, J. M. J.

L. F. Lee, A. Adronov, R. D. Schaller, J. M. J. Fréchet, and R. J. Saykally, “Intermolecular Coupling in Nanometric Domains of Light-Harvesting Dendrimer Films Studied by Photoluminescence Near-Field Scanning Optical Microscopy (PL NSOM) “,” J. Am. Chem. Soc. 125(2), 536–540 (2003).
[Crossref]

Gainsforth, Z.

A. S. McLeod, P. Kelly, M. D. Goldflam, Z. Gainsforth, A. J. Westphal, G. Dominguez, M. H. Thiemens, M. M. Fogler, and D. N. Basov, “Model for quantitative tip-enhanced spectroscopy and the extraction of nanoscale-resolved optical constants,” Phys. Rev. B 90(8), 085136 (2014).
[Crossref]

García-Etxarri, A.

P. Alonso-González, P. Albella, M. Schnell, J. Chen, F. Huth, A. García-Etxarri, F. Casanova, F. Golmar, L. Arzubiaga, L. E. Hueso, J. Aizpurua, and R. Hillenbrand, “Resolving the electromagnetic mechanism of surface-enhanced light scattering at single hot spots,” Nat. Commun. 3(1), 684 (2012).
[Crossref]

Gaussmann, F.

M. Lewin, C. Baeumer, F. Gunkel, A. Schwedt, F. Gaussmann, J. Wueppen, P. Meuffels, B. Jungbluth, J. Mayer, R. Dittmann, R. Waser, and T. Taubner, “Nanospectroscopy of Infrared Phonon Resonance Enables Local Quantification of Electronic Properties in Doped SrTiO3 Ceramics,” Adv. Funct. Mater. 28(42), 1802834 (2018).
[Crossref]

Gensch, M.

S. C. Kehr, J. Döring, M. Gensch, M. Helm, and L. M. Eng, “FEL-Based Near-Field Infrared to THz Nanoscopy,” Sync. Rad. News 30(4), 31–35 (2017).
[Crossref]

Gerton, J. M.

A. Ghimire, E. Shafran, and J. M. Gerton, “Using a sharp metal tip to control the polarization and direction of emission from a quantum dot,” Sci. Rep. 4(1), 6456 (2015).
[Crossref]

Ghimire, A.

A. Ghimire, E. Shafran, and J. M. Gerton, “Using a sharp metal tip to control the polarization and direction of emission from a quantum dot,” Sci. Rep. 4(1), 6456 (2015).
[Crossref]

Goldflam, M. D.

A. S. McLeod, P. Kelly, M. D. Goldflam, Z. Gainsforth, A. J. Westphal, G. Dominguez, M. H. Thiemens, M. M. Fogler, and D. N. Basov, “Model for quantitative tip-enhanced spectroscopy and the extraction of nanoscale-resolved optical constants,” Phys. Rev. B 90(8), 085136 (2014).
[Crossref]

Golmar, F.

P. Alonso-González, P. Albella, M. Schnell, J. Chen, F. Huth, A. García-Etxarri, F. Casanova, F. Golmar, L. Arzubiaga, L. E. Hueso, J. Aizpurua, and R. Hillenbrand, “Resolving the electromagnetic mechanism of surface-enhanced light scattering at single hot spots,” Nat. Commun. 3(1), 684 (2012).
[Crossref]

Gorshunov, B. P.

J. Petzelt, T. Ostapchuk, I. Gregora, I. Rychetský, S. Hoffmann-Eifert, A. V. Pronin, Y. Yuzyuk, B. P. Gorshunov, S. Kamba, V. Bovtun, J. Pokorný, M. Savinov, V. Porokhonskyy, D. Rafaja, P. Vaněk, A. Almeida, M. R. Chaves, A. A. Volkov, M. Dressel, and R. Waser, “Dielectric, infrared, and Raman response of doped SrTiO3 ceramics: Evidence of polar grain boundaries,” Phys. Rev. B 64(18), 184111 (2001).
[Crossref]

Govyadinov, A.

C. Maissen, S. Chen, E. Nikulina, A. Govyadinov, and R. Hillenbrand, “Probes for Ultrasensitive THz Nanoscopy,” ACS Photonics 6(5), 1279–1288 (2019).
[Crossref]

F. Huth, A. Govyadinov, S. Amarie, W. Nuansing, F. Keilmann, and R. Hillenbrand, “Nano-FTIR Absorption Spectroscopy of Molecular Fingerprints at 20 nm Spatial Resolution,” Nano Lett. 12(8), 3973–3978 (2012).
[Crossref]

Grafström, S.

M. T. Wenzel, T. Härtling, P. Olk, S. C. Kehr, S. Grafström, S. Winnerl, M. Helm, and L. M. Eng, “Gold nanoparticle tips for optical field confinement in infrared scattering near-field optical microscopy,” Opt. Express 16(16), 12302–12312 (2008).
[Crossref]

S. C. Kehr, M. Cebula, O. Mieth, T. Härtling, J. Seidel, S. Grafström, L. M. Eng, S. Winnerl, D. Stehr, and M. Helm, “Anisotropy Contrast in Phonon-Enhanced Apertureless Near-Field Microscopy Using a Free-Electron Laser,” Phys. Rev. Lett. 100(25), 256403 (2008).
[Crossref]

S. Schneider, J. Seidel, S. Grafström, L. M. Eng, S. Winnerl, D. Stehr, and M. Helm, “Impact of optical in-plane anisotropy on near-field phonon polariton spectroscopy,” Appl. Phys. Lett. 90(14), 143101 (2007).
[Crossref]

J. Renger, S. Grafström, L. M. Eng, and R. Hillenbrand, “Resonant light scattering by near-field-induced phonon polaritons,” Phys. Rev. B 71(7), 075410 (2005).
[Crossref]

J. Renger, S. Grafström, and L. M. Eng, “Evanescent wave scattering and local electric field enhancement at ellipsoidal silver particles in the vicinity of a glass surface,” J. Opt. Soc. Am. A 21(7), 1362–1367 (2004).
[Crossref]

Gregora, I.

J. Petzelt, T. Ostapchuk, I. Gregora, I. Rychetský, S. Hoffmann-Eifert, A. V. Pronin, Y. Yuzyuk, B. P. Gorshunov, S. Kamba, V. Bovtun, J. Pokorný, M. Savinov, V. Porokhonskyy, D. Rafaja, P. Vaněk, A. Almeida, M. R. Chaves, A. A. Volkov, M. Dressel, and R. Waser, “Dielectric, infrared, and Raman response of doped SrTiO3 ceramics: Evidence of polar grain boundaries,” Phys. Rev. B 64(18), 184111 (2001).
[Crossref]

Gunkel, F.

M. Lewin, C. Baeumer, F. Gunkel, A. Schwedt, F. Gaussmann, J. Wueppen, P. Meuffels, B. Jungbluth, J. Mayer, R. Dittmann, R. Waser, and T. Taubner, “Nanospectroscopy of Infrared Phonon Resonance Enables Local Quantification of Electronic Properties in Doped SrTiO3 Ceramics,” Adv. Funct. Mater. 28(42), 1802834 (2018).
[Crossref]

Hanss, J.

P. Li, X. Yang, T. W. Maß, J. Hanss, M. Lewin, A. K. U. Michel, M. Wuttig, and T. Taubner, “Reversible optical switching of highly confined phonon–polaritons with an ultrathin phase-change material,” Nat. Mater. 15(8), 870–875 (2016).
[Crossref]

Härtling, T.

M. T. Wenzel, T. Härtling, P. Olk, S. C. Kehr, S. Grafström, S. Winnerl, M. Helm, and L. M. Eng, “Gold nanoparticle tips for optical field confinement in infrared scattering near-field optical microscopy,” Opt. Express 16(16), 12302–12312 (2008).
[Crossref]

S. C. Kehr, M. Cebula, O. Mieth, T. Härtling, J. Seidel, S. Grafström, L. M. Eng, S. Winnerl, D. Stehr, and M. Helm, “Anisotropy Contrast in Phonon-Enhanced Apertureless Near-Field Microscopy Using a Free-Electron Laser,” Phys. Rev. Lett. 100(25), 256403 (2008).
[Crossref]

Hartschuh, A.

N. Mauser and A. Hartschuh, “Tip-enhanced near-field optical microscopy,” Chem. Soc. Rev. 43(4), 1248–1262 (2014).
[Crossref]

N. Mauser and A. Hartschuh, “Tip-enhanced near-field optical microscopy,” Chem. Soc. Rev. 43(4), 1248–1262 (2014).
[Crossref]

Helm, M.

S. C. Kehr, J. Döring, M. Gensch, M. Helm, and L. M. Eng, “FEL-Based Near-Field Infrared to THz Nanoscopy,” Sync. Rad. News 30(4), 31–35 (2017).
[Crossref]

S. C. Kehr, M. Cebula, O. Mieth, T. Härtling, J. Seidel, S. Grafström, L. M. Eng, S. Winnerl, D. Stehr, and M. Helm, “Anisotropy Contrast in Phonon-Enhanced Apertureless Near-Field Microscopy Using a Free-Electron Laser,” Phys. Rev. Lett. 100(25), 256403 (2008).
[Crossref]

M. T. Wenzel, T. Härtling, P. Olk, S. C. Kehr, S. Grafström, S. Winnerl, M. Helm, and L. M. Eng, “Gold nanoparticle tips for optical field confinement in infrared scattering near-field optical microscopy,” Opt. Express 16(16), 12302–12312 (2008).
[Crossref]

S. Schneider, J. Seidel, S. Grafström, L. M. Eng, S. Winnerl, D. Stehr, and M. Helm, “Impact of optical in-plane anisotropy on near-field phonon polariton spectroscopy,” Appl. Phys. Lett. 90(14), 143101 (2007).
[Crossref]

Hermann, P.

Hersam, M. C.

M. D. Sonntag, E. A. Pozzi, N. Jiang, M. C. Hersam, and R. P. Van Duyne, “Recent advances in tip-enhanced Raman spectroscopy,” J. Phys. Chem. Lett. 5(18), 3125–3130 (2014).
[Crossref]

Hillenbrand, R.

C. Maissen, S. Chen, E. Nikulina, A. Govyadinov, and R. Hillenbrand, “Probes for Ultrasensitive THz Nanoscopy,” ACS Photonics 6(5), 1279–1288 (2019).
[Crossref]

F. Huth, A. Govyadinov, S. Amarie, W. Nuansing, F. Keilmann, and R. Hillenbrand, “Nano-FTIR Absorption Spectroscopy of Molecular Fingerprints at 20 nm Spatial Resolution,” Nano Lett. 12(8), 3973–3978 (2012).
[Crossref]

P. Alonso-González, P. Albella, M. Schnell, J. Chen, F. Huth, A. García-Etxarri, F. Casanova, F. Golmar, L. Arzubiaga, L. E. Hueso, J. Aizpurua, and R. Hillenbrand, “Resolving the electromagnetic mechanism of surface-enhanced light scattering at single hot spots,” Nat. Commun. 3(1), 684 (2012).
[Crossref]

A. J. Huber, J. Wittborn, and R. Hillenbrand, “Infrared spectroscopic near-field mapping of single nanotransistors,” Nanotechnology 21(23), 235702 (2010).
[Crossref]

A. J. Huber, A. Ziegler, T. Köck, and R. Hillenbrand, “Infrared nanoscopy of strained semiconductors,” Nat. Nanotechnol. 4(3), 153–157 (2009).
[Crossref]

F. Keilmann, A. J. Huber, and R. Hillenbrand, “Nanoscale Conductivity Contrast by Scattering-Type Near-Field Optical Microscopy in the Visible, Infrared and THz Domains,” J. Infrared, Millimeter, Terahertz Waves 30, 1255–1268 (2009).
[Crossref]

A. J. Huber, N. Ocelic, and R. Hillenbrand, “Local excitation and interference of surface phonon polaritons studied by near-field infrared microscopy,” J. Microsc. 229(3), 389–395 (2008).
[Crossref]

A. J. Huber, F. Keilmann, J. Wittborn, J. Aizpurua, and R. Hillenbrand, “Terahertz near-field nanoscopy of mobile carriers in single semiconductor nanodevices,” Nano Lett. 8(11), 3766–3770 (2008).
[Crossref]

A. Cvitkovic, N. Ocelic, and R. Hillenbrand, “Analytical model for quantitative prediction of material contrasts in scattering-type near-field optical microscopy,” Opt. Express 15(14), 8550–8565 (2007).
[Crossref]

M. Brehm, T. Taubner, R. Hillenbrand, and F. Keilmann, “Infrared Spectroscopic Mapping of Single Nanoparticles and Viruses at Nanoscale Resolution,” Nano Lett. 6(7), 1307–1310 (2006).
[Crossref]

J. Renger, S. Grafström, L. M. Eng, and R. Hillenbrand, “Resonant light scattering by near-field-induced phonon polaritons,” Phys. Rev. B 71(7), 075410 (2005).
[Crossref]

T. Taubner, F. Keilmann, and R. Hillenbrand, “Nanomechanical resonance tuning and phase effects in optical near-field interaction,” Nano Lett. 4(9), 1669–1672 (2004).
[Crossref]

T. Taubner, R. Hillenbrand, and F. Keilmann, “Performance of visible and mid-infrared scattering-type near-field optical microscopes,” J. Microsc. 210(3), 311–314 (2003).
[Crossref]

R. Hillenbrand, T. Taubner, and F. Keilmann, “Phonon-enhanced light–matter interaction at the nanometre scale,” Nature 418(6894), 159–162 (2002).
[Crossref]

R. Hillenbrand, B. Knoll, and F. Keilmann, “Pure optical contrast in scattering-type scanning near-field microscopy,” J. Microsc. 202(1), 77–83 (2001).
[Crossref]

Hoehl, A.

Hoffmann-Eifert, S.

J. Petzelt, T. Ostapchuk, I. Gregora, I. Rychetský, S. Hoffmann-Eifert, A. V. Pronin, Y. Yuzyuk, B. P. Gorshunov, S. Kamba, V. Bovtun, J. Pokorný, M. Savinov, V. Porokhonskyy, D. Rafaja, P. Vaněk, A. Almeida, M. R. Chaves, A. A. Volkov, M. Dressel, and R. Waser, “Dielectric, infrared, and Raman response of doped SrTiO3 ceramics: Evidence of polar grain boundaries,” Phys. Rev. B 64(18), 184111 (2001).
[Crossref]

Huber, A. J.

A. J. Huber, J. Wittborn, and R. Hillenbrand, “Infrared spectroscopic near-field mapping of single nanotransistors,” Nanotechnology 21(23), 235702 (2010).
[Crossref]

A. J. Huber, A. Ziegler, T. Köck, and R. Hillenbrand, “Infrared nanoscopy of strained semiconductors,” Nat. Nanotechnol. 4(3), 153–157 (2009).
[Crossref]

F. Keilmann, A. J. Huber, and R. Hillenbrand, “Nanoscale Conductivity Contrast by Scattering-Type Near-Field Optical Microscopy in the Visible, Infrared and THz Domains,” J. Infrared, Millimeter, Terahertz Waves 30, 1255–1268 (2009).
[Crossref]

A. J. Huber, N. Ocelic, and R. Hillenbrand, “Local excitation and interference of surface phonon polaritons studied by near-field infrared microscopy,” J. Microsc. 229(3), 389–395 (2008).
[Crossref]

A. J. Huber, F. Keilmann, J. Wittborn, J. Aizpurua, and R. Hillenbrand, “Terahertz near-field nanoscopy of mobile carriers in single semiconductor nanodevices,” Nano Lett. 8(11), 3766–3770 (2008).
[Crossref]

Hueso, L. E.

P. Alonso-González, P. Albella, M. Schnell, J. Chen, F. Huth, A. García-Etxarri, F. Casanova, F. Golmar, L. Arzubiaga, L. E. Hueso, J. Aizpurua, and R. Hillenbrand, “Resolving the electromagnetic mechanism of surface-enhanced light scattering at single hot spots,” Nat. Commun. 3(1), 684 (2012).
[Crossref]

Huffman, D. R.

C. F. Bohren and D. R. Huffman, “Absorption and Scattering of Light by Small Particles,” WILEY-VCH Verlag GmbH & Co. KGaA, DOI:10.1002/9783527618156 (1998).

Huth, F.

P. Hermann, A. Hoehl, P. Patoka, F. Huth, E. Rühl, and G. Ulm, “Near-field imaging and nano-Fourier-transform infrared spectroscopy using broadband synchrotron radiation,” Opt. Express 21(3), 2913–2919 (2013).
[Crossref]

P. Alonso-González, P. Albella, M. Schnell, J. Chen, F. Huth, A. García-Etxarri, F. Casanova, F. Golmar, L. Arzubiaga, L. E. Hueso, J. Aizpurua, and R. Hillenbrand, “Resolving the electromagnetic mechanism of surface-enhanced light scattering at single hot spots,” Nat. Commun. 3(1), 684 (2012).
[Crossref]

F. Huth, A. Govyadinov, S. Amarie, W. Nuansing, F. Keilmann, and R. Hillenbrand, “Nano-FTIR Absorption Spectroscopy of Molecular Fingerprints at 20 nm Spatial Resolution,” Nano Lett. 12(8), 3973–3978 (2012).
[Crossref]

Ichimura, T.

P. Verma, T. Ichimura, T. Yano, Y. Saito, and S. Kawata, “Nano-imaging through tip-enhanced Raman spectroscopy: Stepping beyond the classical limits,” Laser Photonics Rev. 4(4), 548–561 (2010).
[Crossref]

Jiang, N.

M. D. Sonntag, E. A. Pozzi, N. Jiang, M. C. Hersam, and R. P. Van Duyne, “Recent advances in tip-enhanced Raman spectroscopy,” J. Phys. Chem. Lett. 5(18), 3125–3130 (2014).
[Crossref]

Johnson, T. W.

R. L. Olmon, B. Slovick, T. W. Johnson, D. Shelton, S. -H. Oh, G. D. Boreman, and M. B. Raschke, “Optical dielectric function of gold,” Phys. Rev. B 86, 235147 (2012).
[Crossref]

Jorio, A.

R. Beams, L. G. Cancado, A. Jorio, A. N. Vamivakas, and L. Novotny, “Tip-enhanced Raman mapping of local strain in graphene,” Nanotechnology 26(17), 175702 (2015).
[Crossref]

Jungbluth, B.

M. Lewin, C. Baeumer, F. Gunkel, A. Schwedt, F. Gaussmann, J. Wueppen, P. Meuffels, B. Jungbluth, J. Mayer, R. Dittmann, R. Waser, and T. Taubner, “Nanospectroscopy of Infrared Phonon Resonance Enables Local Quantification of Electronic Properties in Doped SrTiO3 Ceramics,” Adv. Funct. Mater. 28(42), 1802834 (2018).
[Crossref]

Kamba, S.

J. Petzelt, T. Ostapchuk, I. Gregora, I. Rychetský, S. Hoffmann-Eifert, A. V. Pronin, Y. Yuzyuk, B. P. Gorshunov, S. Kamba, V. Bovtun, J. Pokorný, M. Savinov, V. Porokhonskyy, D. Rafaja, P. Vaněk, A. Almeida, M. R. Chaves, A. A. Volkov, M. Dressel, and R. Waser, “Dielectric, infrared, and Raman response of doped SrTiO3 ceramics: Evidence of polar grain boundaries,” Phys. Rev. B 64(18), 184111 (2001).
[Crossref]

Kashcheyevs, V.

Kästner, B.

Kawata, S.

T. Mino, Y. Saito, H. Yoshida, S. Kawata, and P. Verma, “Molecular orientation analysis of organic thin films by z-polarization Raman microscope,” J. Raman Spectrosc. 43(12), 2029–2034 (2012).
[Crossref]

P. Verma, T. Ichimura, T. Yano, Y. Saito, and S. Kawata, “Nano-imaging through tip-enhanced Raman spectroscopy: Stepping beyond the classical limits,” Laser Photonics Rev. 4(4), 548–561 (2010).
[Crossref]

Kehr, S. C.

L. Wehmeier, T. Nörenberg, T. V. A. G. de Oliveira, J. M. Klopf, S. Y. Yang, L. W. Martin, R. Ramesh, L. M. Eng, and S. C. Kehr, “Phonon-induced near-field resonances in multiferroic BiFeO3 thin films at infrared and THz wavelengths,” Appl. Phys. Lett. 116(7), 071103 (2020).
[Crossref]

L. Wehmeier, D. Lang, Y. Liu, X. Zhang, S. Winnerl, L. M. Eng, and S. C. Kehr, “Polarization-dependent near-field phonon nanoscopy of oxides: SrTiO3, LiNbO3, and PbZr0.2Ti0.8O3,” Phys. Rev. B 100(3), 035444 (2019).
[Crossref]

S. C. Kehr, J. Döring, M. Gensch, M. Helm, and L. M. Eng, “FEL-Based Near-Field Infrared to THz Nanoscopy,” Sync. Rad. News 30(4), 31–35 (2017).
[Crossref]

F. Kuschewski, H.-G. von Ribbeck, J. Döring, S. Winnerl, L. M. Eng, and S. C. Kehr, “Narrow-band near-field nanoscopy in the spectral range from 1.3 to 8.5 THz,” Appl. Phys. Lett. 108(11), 113102 (2016).
[Crossref]

M. P. Nikiforov, S. C. Kehr, T. Park, P. Milde, U. Zerweck, C. Loppacher, L. M. Eng, M. J. Therien, N. Engheta, and D. Bonnell, “Probing polarization and dielectric function of molecules with higher order harmonics in scattering–near-field scanning optical microscopy,” J. Appl. Phys. 106(11), 114307 (2009).
[Crossref]

S. C. Kehr, M. Cebula, O. Mieth, T. Härtling, J. Seidel, S. Grafström, L. M. Eng, S. Winnerl, D. Stehr, and M. Helm, “Anisotropy Contrast in Phonon-Enhanced Apertureless Near-Field Microscopy Using a Free-Electron Laser,” Phys. Rev. Lett. 100(25), 256403 (2008).
[Crossref]

M. T. Wenzel, T. Härtling, P. Olk, S. C. Kehr, S. Grafström, S. Winnerl, M. Helm, and L. M. Eng, “Gold nanoparticle tips for optical field confinement in infrared scattering near-field optical microscopy,” Opt. Express 16(16), 12302–12312 (2008).
[Crossref]

Keilmann, F.

P. McArdle, D. J. Lahneman, A. Biswas, F. Keilmann, and M. M. Qazilbash, “Near-field infrared nanospectroscopy of sur-face phonon-polariton resonances,” Phys. Rev. Res. 2(2), 023272 (2020).
[Crossref]

F. Huth, A. Govyadinov, S. Amarie, W. Nuansing, F. Keilmann, and R. Hillenbrand, “Nano-FTIR Absorption Spectroscopy of Molecular Fingerprints at 20 nm Spatial Resolution,” Nano Lett. 12(8), 3973–3978 (2012).
[Crossref]

F. Keilmann, A. J. Huber, and R. Hillenbrand, “Nanoscale Conductivity Contrast by Scattering-Type Near-Field Optical Microscopy in the Visible, Infrared and THz Domains,” J. Infrared, Millimeter, Terahertz Waves 30, 1255–1268 (2009).
[Crossref]

A. J. Huber, F. Keilmann, J. Wittborn, J. Aizpurua, and R. Hillenbrand, “Terahertz near-field nanoscopy of mobile carriers in single semiconductor nanodevices,” Nano Lett. 8(11), 3766–3770 (2008).
[Crossref]

M. Brehm, T. Taubner, R. Hillenbrand, and F. Keilmann, “Infrared Spectroscopic Mapping of Single Nanoparticles and Viruses at Nanoscale Resolution,” Nano Lett. 6(7), 1307–1310 (2006).
[Crossref]

T. Taubner, F. Keilmann, and R. Hillenbrand, “Nanomechanical resonance tuning and phase effects in optical near-field interaction,” Nano Lett. 4(9), 1669–1672 (2004).
[Crossref]

T. Taubner, R. Hillenbrand, and F. Keilmann, “Performance of visible and mid-infrared scattering-type near-field optical microscopes,” J. Microsc. 210(3), 311–314 (2003).
[Crossref]

R. Hillenbrand, T. Taubner, and F. Keilmann, “Phonon-enhanced light–matter interaction at the nanometre scale,” Nature 418(6894), 159–162 (2002).
[Crossref]

R. Hillenbrand, B. Knoll, and F. Keilmann, “Pure optical contrast in scattering-type scanning near-field microscopy,” J. Microsc. 202(1), 77–83 (2001).
[Crossref]

B. Knoll and F. Keilmann, “Enhanced dielectric contrast in scattering-type scanning near-field optical microscopy,” Opt. Commun. 182(4-6), 321–328 (2000).
[Crossref]

B. Knoll and F. Keilmann, “Scanning microscopy by mid-infrared near-field scattering,” Nature 399(6732), 134–137 (1999).
[Crossref]

Kelly, P.

A. S. McLeod, P. Kelly, M. D. Goldflam, Z. Gainsforth, A. J. Westphal, G. Dominguez, M. H. Thiemens, M. M. Fogler, and D. N. Basov, “Model for quantitative tip-enhanced spectroscopy and the extraction of nanoscale-resolved optical constants,” Phys. Rev. B 90(8), 085136 (2014).
[Crossref]

Kern, K.

M. Esslinger, J. Dorfmüller, W. Khunsin, R. Vogelgesang, and K. Kern, “Background-free imaging of plasmonic structures with cross-polarized apertureless scanning near-field optical microscopy,” Rev. Sci. Instrum. 83(3), 033704 (2012).
[Crossref]

Khatib, O.

O. Khatib, H. A. Bechtel, M. C. Martin, M. B. Raschke, and G. Lawrence Carr, “Far infrared synchrotron near-field nanoimaging and nanospectroscopy,” ACS Photonics 5(7), 2773–2779 (2018).
[Crossref]

Khunsin, W.

M. Esslinger, J. Dorfmüller, W. Khunsin, R. Vogelgesang, and K. Kern, “Background-free imaging of plasmonic structures with cross-polarized apertureless scanning near-field optical microscopy,” Rev. Sci. Instrum. 83(3), 033704 (2012).
[Crossref]

Klopf, J. M.

L. Wehmeier, T. Nörenberg, T. V. A. G. de Oliveira, J. M. Klopf, S. Y. Yang, L. W. Martin, R. Ramesh, L. M. Eng, and S. C. Kehr, “Phonon-induced near-field resonances in multiferroic BiFeO3 thin films at infrared and THz wavelengths,” Appl. Phys. Lett. 116(7), 071103 (2020).
[Crossref]

Knoll, B.

R. Hillenbrand, B. Knoll, and F. Keilmann, “Pure optical contrast in scattering-type scanning near-field microscopy,” J. Microsc. 202(1), 77–83 (2001).
[Crossref]

B. Knoll and F. Keilmann, “Enhanced dielectric contrast in scattering-type scanning near-field optical microscopy,” Opt. Commun. 182(4-6), 321–328 (2000).
[Crossref]

B. Knoll and F. Keilmann, “Scanning microscopy by mid-infrared near-field scattering,” Nature 399(6732), 134–137 (1999).
[Crossref]

Köck, T.

A. J. Huber, A. Ziegler, T. Köck, and R. Hillenbrand, “Infrared nanoscopy of strained semiconductors,” Nat. Nanotechnol. 4(3), 153–157 (2009).
[Crossref]

Krenz, P. M.

R. L. Olmon, M. Rang, P. M. Krenz, B. A. Lail, L. V. Saraf, G. D. Boreman, and M. B. Raschke, “Determination of electric-field, magnetic-field, and electric-current distributions of infrared optical antennas: A near-field optical vector network analyser,” Phys. Rev. Lett. 105(16), 167403 (2010).
[Crossref]

Kuipers, L.

N. Rotenberg and L. Kuipers, “Mapping nanoscale light fields,” Nat. Photonics 8(12), 919–926 (2014).
[Crossref]

Kuschewski, F.

F. Kuschewski, H.-G. von Ribbeck, J. Döring, S. Winnerl, L. M. Eng, and S. C. Kehr, “Narrow-band near-field nanoscopy in the spectral range from 1.3 to 8.5 THz,” Appl. Phys. Lett. 108(11), 113102 (2016).
[Crossref]

Lahneman, D. J.

P. McArdle, D. J. Lahneman, A. Biswas, F. Keilmann, and M. M. Qazilbash, “Near-field infrared nanospectroscopy of sur-face phonon-polariton resonances,” Phys. Rev. Res. 2(2), 023272 (2020).
[Crossref]

Lail, B. A.

R. L. Olmon, M. Rang, P. M. Krenz, B. A. Lail, L. V. Saraf, G. D. Boreman, and M. B. Raschke, “Determination of electric-field, magnetic-field, and electric-current distributions of infrared optical antennas: A near-field optical vector network analyser,” Phys. Rev. Lett. 105(16), 167403 (2010).
[Crossref]

Lang, D.

L. Wehmeier, D. Lang, Y. Liu, X. Zhang, S. Winnerl, L. M. Eng, and S. C. Kehr, “Polarization-dependent near-field phonon nanoscopy of oxides: SrTiO3, LiNbO3, and PbZr0.2Ti0.8O3,” Phys. Rev. B 100(3), 035444 (2019).
[Crossref]

Lawrence Carr, G.

O. Khatib, H. A. Bechtel, M. C. Martin, M. B. Raschke, and G. Lawrence Carr, “Far infrared synchrotron near-field nanoimaging and nanospectroscopy,” ACS Photonics 5(7), 2773–2779 (2018).
[Crossref]

Lee, L. F.

L. F. Lee, A. Adronov, R. D. Schaller, J. M. J. Fréchet, and R. J. Saykally, “Intermolecular Coupling in Nanometric Domains of Light-Harvesting Dendrimer Films Studied by Photoluminescence Near-Field Scanning Optical Microscopy (PL NSOM) “,” J. Am. Chem. Soc. 125(2), 536–540 (2003).
[Crossref]

Lewin, M.

M. Lewin, C. Baeumer, F. Gunkel, A. Schwedt, F. Gaussmann, J. Wueppen, P. Meuffels, B. Jungbluth, J. Mayer, R. Dittmann, R. Waser, and T. Taubner, “Nanospectroscopy of Infrared Phonon Resonance Enables Local Quantification of Electronic Properties in Doped SrTiO3 Ceramics,” Adv. Funct. Mater. 28(42), 1802834 (2018).
[Crossref]

P. Li, X. Yang, T. W. Maß, J. Hanss, M. Lewin, A. K. U. Michel, M. Wuttig, and T. Taubner, “Reversible optical switching of highly confined phonon–polaritons with an ultrathin phase-change material,” Nat. Mater. 15(8), 870–875 (2016).
[Crossref]

Li, P.

P. Li, X. Yang, T. W. Maß, J. Hanss, M. Lewin, A. K. U. Michel, M. Wuttig, and T. Taubner, “Reversible optical switching of highly confined phonon–polaritons with an ultrathin phase-change material,” Nat. Mater. 15(8), 870–875 (2016).
[Crossref]

Liu, Y.

L. Wehmeier, D. Lang, Y. Liu, X. Zhang, S. Winnerl, L. M. Eng, and S. C. Kehr, “Polarization-dependent near-field phonon nanoscopy of oxides: SrTiO3, LiNbO3, and PbZr0.2Ti0.8O3,” Phys. Rev. B 100(3), 035444 (2019).
[Crossref]

Loppacher, C.

M. P. Nikiforov, S. C. Kehr, T. Park, P. Milde, U. Zerweck, C. Loppacher, L. M. Eng, M. J. Therien, N. Engheta, and D. Bonnell, “Probing polarization and dielectric function of molecules with higher order harmonics in scattering–near-field scanning optical microscopy,” J. Appl. Phys. 106(11), 114307 (2009).
[Crossref]

Maissen, C.

C. Maissen, S. Chen, E. Nikulina, A. Govyadinov, and R. Hillenbrand, “Probes for Ultrasensitive THz Nanoscopy,” ACS Photonics 6(5), 1279–1288 (2019).
[Crossref]

Martin, L. W.

L. Wehmeier, T. Nörenberg, T. V. A. G. de Oliveira, J. M. Klopf, S. Y. Yang, L. W. Martin, R. Ramesh, L. M. Eng, and S. C. Kehr, “Phonon-induced near-field resonances in multiferroic BiFeO3 thin films at infrared and THz wavelengths,” Appl. Phys. Lett. 116(7), 071103 (2020).
[Crossref]

Martin, M. C.

O. Khatib, H. A. Bechtel, M. C. Martin, M. B. Raschke, and G. Lawrence Carr, “Far infrared synchrotron near-field nanoimaging and nanospectroscopy,” ACS Photonics 5(7), 2773–2779 (2018).
[Crossref]

Martin, Y.

F. Zenhausern, Y. Martin, and H. K. Wickramasinghe, “Scanning Interferometric Apertureless Microscopy: Optical Imaging at 10 Angstrom Resolution,” Science 269(5227), 1083–1085 (1995).
[Crossref]

Martini, J.

R. Eckel, V. Walhorn, C. Pelargus, J. Martini, J. Enderlein, T. Nann, D. Anselmetti, and R. Ros, “Fluorescence-emission control of single CdSe nanocrystals using gold-modified AFM tips,” Small 3(1), 44–49 (2007).
[Crossref]

Maß, T. W.

P. Li, X. Yang, T. W. Maß, J. Hanss, M. Lewin, A. K. U. Michel, M. Wuttig, and T. Taubner, “Reversible optical switching of highly confined phonon–polaritons with an ultrathin phase-change material,” Nat. Mater. 15(8), 870–875 (2016).
[Crossref]

Mauser, N.

N. Mauser and A. Hartschuh, “Tip-enhanced near-field optical microscopy,” Chem. Soc. Rev. 43(4), 1248–1262 (2014).
[Crossref]

N. Mauser and A. Hartschuh, “Tip-enhanced near-field optical microscopy,” Chem. Soc. Rev. 43(4), 1248–1262 (2014).
[Crossref]

Mayer, J.

M. Lewin, C. Baeumer, F. Gunkel, A. Schwedt, F. Gaussmann, J. Wueppen, P. Meuffels, B. Jungbluth, J. Mayer, R. Dittmann, R. Waser, and T. Taubner, “Nanospectroscopy of Infrared Phonon Resonance Enables Local Quantification of Electronic Properties in Doped SrTiO3 Ceramics,” Adv. Funct. Mater. 28(42), 1802834 (2018).
[Crossref]

McArdle, P.

P. McArdle, D. J. Lahneman, A. Biswas, F. Keilmann, and M. M. Qazilbash, “Near-field infrared nanospectroscopy of sur-face phonon-polariton resonances,” Phys. Rev. Res. 2(2), 023272 (2020).
[Crossref]

McLeod, A. S.

A. S. McLeod, P. Kelly, M. D. Goldflam, Z. Gainsforth, A. J. Westphal, G. Dominguez, M. H. Thiemens, M. M. Fogler, and D. N. Basov, “Model for quantitative tip-enhanced spectroscopy and the extraction of nanoscale-resolved optical constants,” Phys. Rev. B 90(8), 085136 (2014).
[Crossref]

Meuffels, P.

M. Lewin, C. Baeumer, F. Gunkel, A. Schwedt, F. Gaussmann, J. Wueppen, P. Meuffels, B. Jungbluth, J. Mayer, R. Dittmann, R. Waser, and T. Taubner, “Nanospectroscopy of Infrared Phonon Resonance Enables Local Quantification of Electronic Properties in Doped SrTiO3 Ceramics,” Adv. Funct. Mater. 28(42), 1802834 (2018).
[Crossref]

Michel, A. K. U.

P. Li, X. Yang, T. W. Maß, J. Hanss, M. Lewin, A. K. U. Michel, M. Wuttig, and T. Taubner, “Reversible optical switching of highly confined phonon–polaritons with an ultrathin phase-change material,” Nat. Mater. 15(8), 870–875 (2016).
[Crossref]

Mieth, O.

S. C. Kehr, M. Cebula, O. Mieth, T. Härtling, J. Seidel, S. Grafström, L. M. Eng, S. Winnerl, D. Stehr, and M. Helm, “Anisotropy Contrast in Phonon-Enhanced Apertureless Near-Field Microscopy Using a Free-Electron Laser,” Phys. Rev. Lett. 100(25), 256403 (2008).
[Crossref]

Milde, P.

M. P. Nikiforov, S. C. Kehr, T. Park, P. Milde, U. Zerweck, C. Loppacher, L. M. Eng, M. J. Therien, N. Engheta, and D. Bonnell, “Probing polarization and dielectric function of molecules with higher order harmonics in scattering–near-field scanning optical microscopy,” J. Appl. Phys. 106(11), 114307 (2009).
[Crossref]

Mino, T.

T. Mino, Y. Saito, and P. Verma, “Quantitative analysis of polarization-controlled tip-enhanced Raman imaging through the evaluation of the tip dipole,” ACS Nano 8(10), 10187–10195 (2014).
[Crossref]

T. Mino, Y. Saito, H. Yoshida, S. Kawata, and P. Verma, “Molecular orientation analysis of organic thin films by z-polarization Raman microscope,” J. Raman Spectrosc. 43(12), 2029–2034 (2012).
[Crossref]

Nann, T.

R. Eckel, V. Walhorn, C. Pelargus, J. Martini, J. Enderlein, T. Nann, D. Anselmetti, and R. Ros, “Fluorescence-emission control of single CdSe nanocrystals using gold-modified AFM tips,” Small 3(1), 44–49 (2007).
[Crossref]

Nikiforov, M. P.

M. P. Nikiforov, S. C. Kehr, T. Park, P. Milde, U. Zerweck, C. Loppacher, L. M. Eng, M. J. Therien, N. Engheta, and D. Bonnell, “Probing polarization and dielectric function of molecules with higher order harmonics in scattering–near-field scanning optical microscopy,” J. Appl. Phys. 106(11), 114307 (2009).
[Crossref]

Nikulina, E.

C. Maissen, S. Chen, E. Nikulina, A. Govyadinov, and R. Hillenbrand, “Probes for Ultrasensitive THz Nanoscopy,” ACS Photonics 6(5), 1279–1288 (2019).
[Crossref]

Nörenberg, T.

L. Wehmeier, T. Nörenberg, T. V. A. G. de Oliveira, J. M. Klopf, S. Y. Yang, L. W. Martin, R. Ramesh, L. M. Eng, and S. C. Kehr, “Phonon-induced near-field resonances in multiferroic BiFeO3 thin films at infrared and THz wavelengths,” Appl. Phys. Lett. 116(7), 071103 (2020).
[Crossref]

Novotny, L.

R. Beams, L. G. Cancado, A. Jorio, A. N. Vamivakas, and L. Novotny, “Tip-enhanced Raman mapping of local strain in graphene,” Nanotechnology 26(17), 175702 (2015).
[Crossref]

P. Anger, P. Bharadwaj, and L. Novotny, “Enhancement and quenching of single-molecule fluorescence,” Phys. Rev. Lett. 96(11), 113002 (2006).
[Crossref]

Nuansing, W.

F. Huth, A. Govyadinov, S. Amarie, W. Nuansing, F. Keilmann, and R. Hillenbrand, “Nano-FTIR Absorption Spectroscopy of Molecular Fingerprints at 20 nm Spatial Resolution,” Nano Lett. 12(8), 3973–3978 (2012).
[Crossref]

Ocelic, N.

A. J. Huber, N. Ocelic, and R. Hillenbrand, “Local excitation and interference of surface phonon polaritons studied by near-field infrared microscopy,” J. Microsc. 229(3), 389–395 (2008).
[Crossref]

A. Cvitkovic, N. Ocelic, and R. Hillenbrand, “Analytical model for quantitative prediction of material contrasts in scattering-type near-field optical microscopy,” Opt. Express 15(14), 8550–8565 (2007).
[Crossref]

Oh, S. -H.

R. L. Olmon, B. Slovick, T. W. Johnson, D. Shelton, S. -H. Oh, G. D. Boreman, and M. B. Raschke, “Optical dielectric function of gold,” Phys. Rev. B 86, 235147 (2012).
[Crossref]

Olk, P.

Olmon, R. L.

R. L. Olmon, B. Slovick, T. W. Johnson, D. Shelton, S. -H. Oh, G. D. Boreman, and M. B. Raschke, “Optical dielectric function of gold,” Phys. Rev. B 86, 235147 (2012).
[Crossref]

S. Berweger, J. M. Atkin, R. L. Olmon, and M. B. Raschke, “Light on the tip of a needle: Plasmonic nanofocusing for spectroscopy on the nanoscale,” J. Phys. Chem. Lett. 3(7), 945–952 (2012).
[Crossref]

R. L. Olmon, M. Rang, P. M. Krenz, B. A. Lail, L. V. Saraf, G. D. Boreman, and M. B. Raschke, “Determination of electric-field, magnetic-field, and electric-current distributions of infrared optical antennas: A near-field optical vector network analyser,” Phys. Rev. Lett. 105(16), 167403 (2010).
[Crossref]

Ostapchuk, T.

J. Petzelt, T. Ostapchuk, I. Gregora, I. Rychetský, S. Hoffmann-Eifert, A. V. Pronin, Y. Yuzyuk, B. P. Gorshunov, S. Kamba, V. Bovtun, J. Pokorný, M. Savinov, V. Porokhonskyy, D. Rafaja, P. Vaněk, A. Almeida, M. R. Chaves, A. A. Volkov, M. Dressel, and R. Waser, “Dielectric, infrared, and Raman response of doped SrTiO3 ceramics: Evidence of polar grain boundaries,” Phys. Rev. B 64(18), 184111 (2001).
[Crossref]

Park, K.-D.

K.-D. Park and M. B. Raschke, “Polarization control with plasmonic antenna-tips: A universal approach for optical nano-crystallography and vector-field imaging,” Nano Lett. 18(5), 2912–2917 (2018).
[Crossref]

Park, T.

M. P. Nikiforov, S. C. Kehr, T. Park, P. Milde, U. Zerweck, C. Loppacher, L. M. Eng, M. J. Therien, N. Engheta, and D. Bonnell, “Probing polarization and dielectric function of molecules with higher order harmonics in scattering–near-field scanning optical microscopy,” J. Appl. Phys. 106(11), 114307 (2009).
[Crossref]

Patoka, P.

Pelargus, C.

R. Eckel, V. Walhorn, C. Pelargus, J. Martini, J. Enderlein, T. Nann, D. Anselmetti, and R. Ros, “Fluorescence-emission control of single CdSe nanocrystals using gold-modified AFM tips,” Small 3(1), 44–49 (2007).
[Crossref]

Petzelt, J.

J. Petzelt, T. Ostapchuk, I. Gregora, I. Rychetský, S. Hoffmann-Eifert, A. V. Pronin, Y. Yuzyuk, B. P. Gorshunov, S. Kamba, V. Bovtun, J. Pokorný, M. Savinov, V. Porokhonskyy, D. Rafaja, P. Vaněk, A. Almeida, M. R. Chaves, A. A. Volkov, M. Dressel, and R. Waser, “Dielectric, infrared, and Raman response of doped SrTiO3 ceramics: Evidence of polar grain boundaries,” Phys. Rev. B 64(18), 184111 (2001).
[Crossref]

Pokorný, J.

J. Petzelt, T. Ostapchuk, I. Gregora, I. Rychetský, S. Hoffmann-Eifert, A. V. Pronin, Y. Yuzyuk, B. P. Gorshunov, S. Kamba, V. Bovtun, J. Pokorný, M. Savinov, V. Porokhonskyy, D. Rafaja, P. Vaněk, A. Almeida, M. R. Chaves, A. A. Volkov, M. Dressel, and R. Waser, “Dielectric, infrared, and Raman response of doped SrTiO3 ceramics: Evidence of polar grain boundaries,” Phys. Rev. B 64(18), 184111 (2001).
[Crossref]

Porokhonskyy, V.

J. Petzelt, T. Ostapchuk, I. Gregora, I. Rychetský, S. Hoffmann-Eifert, A. V. Pronin, Y. Yuzyuk, B. P. Gorshunov, S. Kamba, V. Bovtun, J. Pokorný, M. Savinov, V. Porokhonskyy, D. Rafaja, P. Vaněk, A. Almeida, M. R. Chaves, A. A. Volkov, M. Dressel, and R. Waser, “Dielectric, infrared, and Raman response of doped SrTiO3 ceramics: Evidence of polar grain boundaries,” Phys. Rev. B 64(18), 184111 (2001).
[Crossref]

Pozzi, E. A.

M. D. Sonntag, E. A. Pozzi, N. Jiang, M. C. Hersam, and R. P. Van Duyne, “Recent advances in tip-enhanced Raman spectroscopy,” J. Phys. Chem. Lett. 5(18), 3125–3130 (2014).
[Crossref]

Pronin, A. V.

J. Petzelt, T. Ostapchuk, I. Gregora, I. Rychetský, S. Hoffmann-Eifert, A. V. Pronin, Y. Yuzyuk, B. P. Gorshunov, S. Kamba, V. Bovtun, J. Pokorný, M. Savinov, V. Porokhonskyy, D. Rafaja, P. Vaněk, A. Almeida, M. R. Chaves, A. A. Volkov, M. Dressel, and R. Waser, “Dielectric, infrared, and Raman response of doped SrTiO3 ceramics: Evidence of polar grain boundaries,” Phys. Rev. B 64(18), 184111 (2001).
[Crossref]

Qazilbash, M. M.

P. McArdle, D. J. Lahneman, A. Biswas, F. Keilmann, and M. M. Qazilbash, “Near-field infrared nanospectroscopy of sur-face phonon-polariton resonances,” Phys. Rev. Res. 2(2), 023272 (2020).
[Crossref]

Rafaja, D.

J. Petzelt, T. Ostapchuk, I. Gregora, I. Rychetský, S. Hoffmann-Eifert, A. V. Pronin, Y. Yuzyuk, B. P. Gorshunov, S. Kamba, V. Bovtun, J. Pokorný, M. Savinov, V. Porokhonskyy, D. Rafaja, P. Vaněk, A. Almeida, M. R. Chaves, A. A. Volkov, M. Dressel, and R. Waser, “Dielectric, infrared, and Raman response of doped SrTiO3 ceramics: Evidence of polar grain boundaries,” Phys. Rev. B 64(18), 184111 (2001).
[Crossref]

Ramesh, R.

L. Wehmeier, T. Nörenberg, T. V. A. G. de Oliveira, J. M. Klopf, S. Y. Yang, L. W. Martin, R. Ramesh, L. M. Eng, and S. C. Kehr, “Phonon-induced near-field resonances in multiferroic BiFeO3 thin films at infrared and THz wavelengths,” Appl. Phys. Lett. 116(7), 071103 (2020).
[Crossref]

Rang, M.

R. L. Olmon, M. Rang, P. M. Krenz, B. A. Lail, L. V. Saraf, G. D. Boreman, and M. B. Raschke, “Determination of electric-field, magnetic-field, and electric-current distributions of infrared optical antennas: A near-field optical vector network analyser,” Phys. Rev. Lett. 105(16), 167403 (2010).
[Crossref]

Raschke, M. B.

K.-D. Park and M. B. Raschke, “Polarization control with plasmonic antenna-tips: A universal approach for optical nano-crystallography and vector-field imaging,” Nano Lett. 18(5), 2912–2917 (2018).
[Crossref]

O. Khatib, H. A. Bechtel, M. C. Martin, M. B. Raschke, and G. Lawrence Carr, “Far infrared synchrotron near-field nanoimaging and nanospectroscopy,” ACS Photonics 5(7), 2773–2779 (2018).
[Crossref]

S. Berweger, J. M. Atkin, R. L. Olmon, and M. B. Raschke, “Light on the tip of a needle: Plasmonic nanofocusing for spectroscopy on the nanoscale,” J. Phys. Chem. Lett. 3(7), 945–952 (2012).
[Crossref]

R. L. Olmon, B. Slovick, T. W. Johnson, D. Shelton, S. -H. Oh, G. D. Boreman, and M. B. Raschke, “Optical dielectric function of gold,” Phys. Rev. B 86, 235147 (2012).
[Crossref]

R. L. Olmon, M. Rang, P. M. Krenz, B. A. Lail, L. V. Saraf, G. D. Boreman, and M. B. Raschke, “Determination of electric-field, magnetic-field, and electric-current distributions of infrared optical antennas: A near-field optical vector network analyser,” Phys. Rev. Lett. 105(16), 167403 (2010).
[Crossref]

S. Berweger and M. B. Raschke, “Polar Phonon Mode Selection. Rules in Tip-Enhanced Raman Scattering,” J. Raman Spectrosc. 40(10), 1413–1419 (2009).
[Crossref]

Renger, J.

J. Renger, S. Grafström, L. M. Eng, and R. Hillenbrand, “Resonant light scattering by near-field-induced phonon polaritons,” Phys. Rev. B 71(7), 075410 (2005).
[Crossref]

J. Renger, S. Grafström, and L. M. Eng, “Evanescent wave scattering and local electric field enhancement at ellipsoidal silver particles in the vicinity of a glass surface,” J. Opt. Soc. Am. A 21(7), 1362–1367 (2004).
[Crossref]

Rickman, R. H.

R. H. Rickman and P. R. Dunstan, “Enhancement of lattice defect signatures in graphene and ultrathin graphite using tip-enhanced Raman spectroscopy,” J. Raman Spectrosc. 45(1), 15–21 (2014).
[Crossref]

Ries, M.

Ros, R.

R. Eckel, V. Walhorn, C. Pelargus, J. Martini, J. Enderlein, T. Nann, D. Anselmetti, and R. Ros, “Fluorescence-emission control of single CdSe nanocrystals using gold-modified AFM tips,” Small 3(1), 44–49 (2007).
[Crossref]

Rotenberg, N.

N. Rotenberg and L. Kuipers, “Mapping nanoscale light fields,” Nat. Photonics 8(12), 919–926 (2014).
[Crossref]

Rühl, E.

Rychetský, I.

J. Petzelt, T. Ostapchuk, I. Gregora, I. Rychetský, S. Hoffmann-Eifert, A. V. Pronin, Y. Yuzyuk, B. P. Gorshunov, S. Kamba, V. Bovtun, J. Pokorný, M. Savinov, V. Porokhonskyy, D. Rafaja, P. Vaněk, A. Almeida, M. R. Chaves, A. A. Volkov, M. Dressel, and R. Waser, “Dielectric, infrared, and Raman response of doped SrTiO3 ceramics: Evidence of polar grain boundaries,” Phys. Rev. B 64(18), 184111 (2001).
[Crossref]

Saito, Y.

T. Mino, Y. Saito, and P. Verma, “Quantitative analysis of polarization-controlled tip-enhanced Raman imaging through the evaluation of the tip dipole,” ACS Nano 8(10), 10187–10195 (2014).
[Crossref]

Y. Saito and P. Verma, “Polarization-controlled Raman microscopy and nanoscopy,” J. Phys. Chem. Lett. 3(10), 1295–1300 (2012).
[Crossref]

T. Mino, Y. Saito, H. Yoshida, S. Kawata, and P. Verma, “Molecular orientation analysis of organic thin films by z-polarization Raman microscope,” J. Raman Spectrosc. 43(12), 2029–2034 (2012).
[Crossref]

P. Verma, T. Ichimura, T. Yano, Y. Saito, and S. Kawata, “Nano-imaging through tip-enhanced Raman spectroscopy: Stepping beyond the classical limits,” Laser Photonics Rev. 4(4), 548–561 (2010).
[Crossref]

Saraf, L. V.

R. L. Olmon, M. Rang, P. M. Krenz, B. A. Lail, L. V. Saraf, G. D. Boreman, and M. B. Raschke, “Determination of electric-field, magnetic-field, and electric-current distributions of infrared optical antennas: A near-field optical vector network analyser,” Phys. Rev. Lett. 105(16), 167403 (2010).
[Crossref]

Savinov, M.

J. Petzelt, T. Ostapchuk, I. Gregora, I. Rychetský, S. Hoffmann-Eifert, A. V. Pronin, Y. Yuzyuk, B. P. Gorshunov, S. Kamba, V. Bovtun, J. Pokorný, M. Savinov, V. Porokhonskyy, D. Rafaja, P. Vaněk, A. Almeida, M. R. Chaves, A. A. Volkov, M. Dressel, and R. Waser, “Dielectric, infrared, and Raman response of doped SrTiO3 ceramics: Evidence of polar grain boundaries,” Phys. Rev. B 64(18), 184111 (2001).
[Crossref]

Saykally, R. J.

L. F. Lee, A. Adronov, R. D. Schaller, J. M. J. Fréchet, and R. J. Saykally, “Intermolecular Coupling in Nanometric Domains of Light-Harvesting Dendrimer Films Studied by Photoluminescence Near-Field Scanning Optical Microscopy (PL NSOM) “,” J. Am. Chem. Soc. 125(2), 536–540 (2003).
[Crossref]

Schaller, R. D.

L. F. Lee, A. Adronov, R. D. Schaller, J. M. J. Fréchet, and R. J. Saykally, “Intermolecular Coupling in Nanometric Domains of Light-Harvesting Dendrimer Films Studied by Photoluminescence Near-Field Scanning Optical Microscopy (PL NSOM) “,” J. Am. Chem. Soc. 125(2), 536–540 (2003).
[Crossref]

Schmid, T.

J. Stadler, T. Schmid, and R. Zenobi, “Developments in and practical guidelines for tip-enhanced Raman spectroscopy,” Nanoscale 4(6), 1856–1870 (2012).
[Crossref]

Schneider, S.

S. Schneider, J. Seidel, S. Grafström, L. M. Eng, S. Winnerl, D. Stehr, and M. Helm, “Impact of optical in-plane anisotropy on near-field phonon polariton spectroscopy,” Appl. Phys. Lett. 90(14), 143101 (2007).
[Crossref]

Schnell, M.

P. Alonso-González, P. Albella, M. Schnell, J. Chen, F. Huth, A. García-Etxarri, F. Casanova, F. Golmar, L. Arzubiaga, L. E. Hueso, J. Aizpurua, and R. Hillenbrand, “Resolving the electromagnetic mechanism of surface-enhanced light scattering at single hot spots,” Nat. Commun. 3(1), 684 (2012).
[Crossref]

Schwedt, A.

M. Lewin, C. Baeumer, F. Gunkel, A. Schwedt, F. Gaussmann, J. Wueppen, P. Meuffels, B. Jungbluth, J. Mayer, R. Dittmann, R. Waser, and T. Taubner, “Nanospectroscopy of Infrared Phonon Resonance Enables Local Quantification of Electronic Properties in Doped SrTiO3 Ceramics,” Adv. Funct. Mater. 28(42), 1802834 (2018).
[Crossref]

Seidel, J.

S. C. Kehr, M. Cebula, O. Mieth, T. Härtling, J. Seidel, S. Grafström, L. M. Eng, S. Winnerl, D. Stehr, and M. Helm, “Anisotropy Contrast in Phonon-Enhanced Apertureless Near-Field Microscopy Using a Free-Electron Laser,” Phys. Rev. Lett. 100(25), 256403 (2008).
[Crossref]

S. Schneider, J. Seidel, S. Grafström, L. M. Eng, S. Winnerl, D. Stehr, and M. Helm, “Impact of optical in-plane anisotropy on near-field phonon polariton spectroscopy,” Appl. Phys. Lett. 90(14), 143101 (2007).
[Crossref]

Shafran, E.

A. Ghimire, E. Shafran, and J. M. Gerton, “Using a sharp metal tip to control the polarization and direction of emission from a quantum dot,” Sci. Rep. 4(1), 6456 (2015).
[Crossref]

Shelton, D.

R. L. Olmon, B. Slovick, T. W. Johnson, D. Shelton, S. -H. Oh, G. D. Boreman, and M. B. Raschke, “Optical dielectric function of gold,” Phys. Rev. B 86, 235147 (2012).
[Crossref]

Slovick, B.

R. L. Olmon, B. Slovick, T. W. Johnson, D. Shelton, S. -H. Oh, G. D. Boreman, and M. B. Raschke, “Optical dielectric function of gold,” Phys. Rev. B 86, 235147 (2012).
[Crossref]

Sonntag, M. D.

M. D. Sonntag, E. A. Pozzi, N. Jiang, M. C. Hersam, and R. P. Van Duyne, “Recent advances in tip-enhanced Raman spectroscopy,” J. Phys. Chem. Lett. 5(18), 3125–3130 (2014).
[Crossref]

Stadler, J.

J. Stadler, T. Schmid, and R. Zenobi, “Developments in and practical guidelines for tip-enhanced Raman spectroscopy,” Nanoscale 4(6), 1856–1870 (2012).
[Crossref]

Stehr, D.

S. C. Kehr, M. Cebula, O. Mieth, T. Härtling, J. Seidel, S. Grafström, L. M. Eng, S. Winnerl, D. Stehr, and M. Helm, “Anisotropy Contrast in Phonon-Enhanced Apertureless Near-Field Microscopy Using a Free-Electron Laser,” Phys. Rev. Lett. 100(25), 256403 (2008).
[Crossref]

S. Schneider, J. Seidel, S. Grafström, L. M. Eng, S. Winnerl, D. Stehr, and M. Helm, “Impact of optical in-plane anisotropy on near-field phonon polariton spectroscopy,” Appl. Phys. Lett. 90(14), 143101 (2007).
[Crossref]

Stockman, M. I.

M. I. Stockman, “Nanofocusing of optical energy in tapered plasmonic waveguides,” Phys. Rev. Lett. 93(13), 137404 (2004).
[Crossref]

Taubner, T.

M. Lewin, C. Baeumer, F. Gunkel, A. Schwedt, F. Gaussmann, J. Wueppen, P. Meuffels, B. Jungbluth, J. Mayer, R. Dittmann, R. Waser, and T. Taubner, “Nanospectroscopy of Infrared Phonon Resonance Enables Local Quantification of Electronic Properties in Doped SrTiO3 Ceramics,” Adv. Funct. Mater. 28(42), 1802834 (2018).
[Crossref]

P. Li, X. Yang, T. W. Maß, J. Hanss, M. Lewin, A. K. U. Michel, M. Wuttig, and T. Taubner, “Reversible optical switching of highly confined phonon–polaritons with an ultrathin phase-change material,” Nat. Mater. 15(8), 870–875 (2016).
[Crossref]

M. Brehm, T. Taubner, R. Hillenbrand, and F. Keilmann, “Infrared Spectroscopic Mapping of Single Nanoparticles and Viruses at Nanoscale Resolution,” Nano Lett. 6(7), 1307–1310 (2006).
[Crossref]

T. Taubner, F. Keilmann, and R. Hillenbrand, “Nanomechanical resonance tuning and phase effects in optical near-field interaction,” Nano Lett. 4(9), 1669–1672 (2004).
[Crossref]

T. Taubner, R. Hillenbrand, and F. Keilmann, “Performance of visible and mid-infrared scattering-type near-field optical microscopes,” J. Microsc. 210(3), 311–314 (2003).
[Crossref]

R. Hillenbrand, T. Taubner, and F. Keilmann, “Phonon-enhanced light–matter interaction at the nanometre scale,” Nature 418(6894), 159–162 (2002).
[Crossref]

Therien, M. J.

M. P. Nikiforov, S. C. Kehr, T. Park, P. Milde, U. Zerweck, C. Loppacher, L. M. Eng, M. J. Therien, N. Engheta, and D. Bonnell, “Probing polarization and dielectric function of molecules with higher order harmonics in scattering–near-field scanning optical microscopy,” J. Appl. Phys. 106(11), 114307 (2009).
[Crossref]

Thiemens, M. H.

A. S. McLeod, P. Kelly, M. D. Goldflam, Z. Gainsforth, A. J. Westphal, G. Dominguez, M. H. Thiemens, M. M. Fogler, and D. N. Basov, “Model for quantitative tip-enhanced spectroscopy and the extraction of nanoscale-resolved optical constants,” Phys. Rev. B 90(8), 085136 (2014).
[Crossref]

Tydecks, T.

Ulm, G.

Ulrich, G.

Vamivakas, A. N.

R. Beams, L. G. Cancado, A. Jorio, A. N. Vamivakas, and L. Novotny, “Tip-enhanced Raman mapping of local strain in graphene,” Nanotechnology 26(17), 175702 (2015).
[Crossref]

Van Duyne, R. P.

M. D. Sonntag, E. A. Pozzi, N. Jiang, M. C. Hersam, and R. P. Van Duyne, “Recent advances in tip-enhanced Raman spectroscopy,” J. Phys. Chem. Lett. 5(18), 3125–3130 (2014).
[Crossref]

Vanek, P.

J. Petzelt, T. Ostapchuk, I. Gregora, I. Rychetský, S. Hoffmann-Eifert, A. V. Pronin, Y. Yuzyuk, B. P. Gorshunov, S. Kamba, V. Bovtun, J. Pokorný, M. Savinov, V. Porokhonskyy, D. Rafaja, P. Vaněk, A. Almeida, M. R. Chaves, A. A. Volkov, M. Dressel, and R. Waser, “Dielectric, infrared, and Raman response of doped SrTiO3 ceramics: Evidence of polar grain boundaries,” Phys. Rev. B 64(18), 184111 (2001).
[Crossref]

Verma, P.

T. Mino, Y. Saito, and P. Verma, “Quantitative analysis of polarization-controlled tip-enhanced Raman imaging through the evaluation of the tip dipole,” ACS Nano 8(10), 10187–10195 (2014).
[Crossref]

Y. Saito and P. Verma, “Polarization-controlled Raman microscopy and nanoscopy,” J. Phys. Chem. Lett. 3(10), 1295–1300 (2012).
[Crossref]

T. Mino, Y. Saito, H. Yoshida, S. Kawata, and P. Verma, “Molecular orientation analysis of organic thin films by z-polarization Raman microscope,” J. Raman Spectrosc. 43(12), 2029–2034 (2012).
[Crossref]

P. Verma, T. Ichimura, T. Yano, Y. Saito, and S. Kawata, “Nano-imaging through tip-enhanced Raman spectroscopy: Stepping beyond the classical limits,” Laser Photonics Rev. 4(4), 548–561 (2010).
[Crossref]

Vogelgesang, R.

M. Esslinger, J. Dorfmüller, W. Khunsin, R. Vogelgesang, and K. Kern, “Background-free imaging of plasmonic structures with cross-polarized apertureless scanning near-field optical microscopy,” Rev. Sci. Instrum. 83(3), 033704 (2012).
[Crossref]

Volkov, A. A.

J. Petzelt, T. Ostapchuk, I. Gregora, I. Rychetský, S. Hoffmann-Eifert, A. V. Pronin, Y. Yuzyuk, B. P. Gorshunov, S. Kamba, V. Bovtun, J. Pokorný, M. Savinov, V. Porokhonskyy, D. Rafaja, P. Vaněk, A. Almeida, M. R. Chaves, A. A. Volkov, M. Dressel, and R. Waser, “Dielectric, infrared, and Raman response of doped SrTiO3 ceramics: Evidence of polar grain boundaries,” Phys. Rev. B 64(18), 184111 (2001).
[Crossref]

von Ribbeck, H.-G.

F. Kuschewski, H.-G. von Ribbeck, J. Döring, S. Winnerl, L. M. Eng, and S. C. Kehr, “Narrow-band near-field nanoscopy in the spectral range from 1.3 to 8.5 THz,” Appl. Phys. Lett. 108(11), 113102 (2016).
[Crossref]

Walhorn, V.

R. Eckel, V. Walhorn, C. Pelargus, J. Martini, J. Enderlein, T. Nann, D. Anselmetti, and R. Ros, “Fluorescence-emission control of single CdSe nanocrystals using gold-modified AFM tips,” Small 3(1), 44–49 (2007).
[Crossref]

Waser, R.

M. Lewin, C. Baeumer, F. Gunkel, A. Schwedt, F. Gaussmann, J. Wueppen, P. Meuffels, B. Jungbluth, J. Mayer, R. Dittmann, R. Waser, and T. Taubner, “Nanospectroscopy of Infrared Phonon Resonance Enables Local Quantification of Electronic Properties in Doped SrTiO3 Ceramics,” Adv. Funct. Mater. 28(42), 1802834 (2018).
[Crossref]

J. Petzelt, T. Ostapchuk, I. Gregora, I. Rychetský, S. Hoffmann-Eifert, A. V. Pronin, Y. Yuzyuk, B. P. Gorshunov, S. Kamba, V. Bovtun, J. Pokorný, M. Savinov, V. Porokhonskyy, D. Rafaja, P. Vaněk, A. Almeida, M. R. Chaves, A. A. Volkov, M. Dressel, and R. Waser, “Dielectric, infrared, and Raman response of doped SrTiO3 ceramics: Evidence of polar grain boundaries,” Phys. Rev. B 64(18), 184111 (2001).
[Crossref]

Wehmeier, L.

L. Wehmeier, T. Nörenberg, T. V. A. G. de Oliveira, J. M. Klopf, S. Y. Yang, L. W. Martin, R. Ramesh, L. M. Eng, and S. C. Kehr, “Phonon-induced near-field resonances in multiferroic BiFeO3 thin films at infrared and THz wavelengths,” Appl. Phys. Lett. 116(7), 071103 (2020).
[Crossref]

L. Wehmeier, D. Lang, Y. Liu, X. Zhang, S. Winnerl, L. M. Eng, and S. C. Kehr, “Polarization-dependent near-field phonon nanoscopy of oxides: SrTiO3, LiNbO3, and PbZr0.2Ti0.8O3,” Phys. Rev. B 100(3), 035444 (2019).
[Crossref]

Wenzel, M. T.

Westphal, A. J.

A. S. McLeod, P. Kelly, M. D. Goldflam, Z. Gainsforth, A. J. Westphal, G. Dominguez, M. H. Thiemens, M. M. Fogler, and D. N. Basov, “Model for quantitative tip-enhanced spectroscopy and the extraction of nanoscale-resolved optical constants,” Phys. Rev. B 90(8), 085136 (2014).
[Crossref]

Wickramasinghe, H. K.

F. Zenhausern, Y. Martin, and H. K. Wickramasinghe, “Scanning Interferometric Apertureless Microscopy: Optical Imaging at 10 Angstrom Resolution,” Science 269(5227), 1083–1085 (1995).
[Crossref]

Winnerl, S.

L. Wehmeier, D. Lang, Y. Liu, X. Zhang, S. Winnerl, L. M. Eng, and S. C. Kehr, “Polarization-dependent near-field phonon nanoscopy of oxides: SrTiO3, LiNbO3, and PbZr0.2Ti0.8O3,” Phys. Rev. B 100(3), 035444 (2019).
[Crossref]

F. Kuschewski, H.-G. von Ribbeck, J. Döring, S. Winnerl, L. M. Eng, and S. C. Kehr, “Narrow-band near-field nanoscopy in the spectral range from 1.3 to 8.5 THz,” Appl. Phys. Lett. 108(11), 113102 (2016).
[Crossref]

S. C. Kehr, M. Cebula, O. Mieth, T. Härtling, J. Seidel, S. Grafström, L. M. Eng, S. Winnerl, D. Stehr, and M. Helm, “Anisotropy Contrast in Phonon-Enhanced Apertureless Near-Field Microscopy Using a Free-Electron Laser,” Phys. Rev. Lett. 100(25), 256403 (2008).
[Crossref]

M. T. Wenzel, T. Härtling, P. Olk, S. C. Kehr, S. Grafström, S. Winnerl, M. Helm, and L. M. Eng, “Gold nanoparticle tips for optical field confinement in infrared scattering near-field optical microscopy,” Opt. Express 16(16), 12302–12312 (2008).
[Crossref]

S. Schneider, J. Seidel, S. Grafström, L. M. Eng, S. Winnerl, D. Stehr, and M. Helm, “Impact of optical in-plane anisotropy on near-field phonon polariton spectroscopy,” Appl. Phys. Lett. 90(14), 143101 (2007).
[Crossref]

Wittborn, J.

A. J. Huber, J. Wittborn, and R. Hillenbrand, “Infrared spectroscopic near-field mapping of single nanotransistors,” Nanotechnology 21(23), 235702 (2010).
[Crossref]

A. J. Huber, F. Keilmann, J. Wittborn, J. Aizpurua, and R. Hillenbrand, “Terahertz near-field nanoscopy of mobile carriers in single semiconductor nanodevices,” Nano Lett. 8(11), 3766–3770 (2008).
[Crossref]

Wueppen, J.

M. Lewin, C. Baeumer, F. Gunkel, A. Schwedt, F. Gaussmann, J. Wueppen, P. Meuffels, B. Jungbluth, J. Mayer, R. Dittmann, R. Waser, and T. Taubner, “Nanospectroscopy of Infrared Phonon Resonance Enables Local Quantification of Electronic Properties in Doped SrTiO3 Ceramics,” Adv. Funct. Mater. 28(42), 1802834 (2018).
[Crossref]

Wuttig, M.

P. Li, X. Yang, T. W. Maß, J. Hanss, M. Lewin, A. K. U. Michel, M. Wuttig, and T. Taubner, “Reversible optical switching of highly confined phonon–polaritons with an ultrathin phase-change material,” Nat. Mater. 15(8), 870–875 (2016).
[Crossref]

Yang, S. Y.

L. Wehmeier, T. Nörenberg, T. V. A. G. de Oliveira, J. M. Klopf, S. Y. Yang, L. W. Martin, R. Ramesh, L. M. Eng, and S. C. Kehr, “Phonon-induced near-field resonances in multiferroic BiFeO3 thin films at infrared and THz wavelengths,” Appl. Phys. Lett. 116(7), 071103 (2020).
[Crossref]

Yang, X.

P. Li, X. Yang, T. W. Maß, J. Hanss, M. Lewin, A. K. U. Michel, M. Wuttig, and T. Taubner, “Reversible optical switching of highly confined phonon–polaritons with an ultrathin phase-change material,” Nat. Mater. 15(8), 870–875 (2016).
[Crossref]

Yano, T.

P. Verma, T. Ichimura, T. Yano, Y. Saito, and S. Kawata, “Nano-imaging through tip-enhanced Raman spectroscopy: Stepping beyond the classical limits,” Laser Photonics Rev. 4(4), 548–561 (2010).
[Crossref]

Yoshida, H.

T. Mino, Y. Saito, H. Yoshida, S. Kawata, and P. Verma, “Molecular orientation analysis of organic thin films by z-polarization Raman microscope,” J. Raman Spectrosc. 43(12), 2029–2034 (2012).
[Crossref]

Yuzyuk, Y.

J. Petzelt, T. Ostapchuk, I. Gregora, I. Rychetský, S. Hoffmann-Eifert, A. V. Pronin, Y. Yuzyuk, B. P. Gorshunov, S. Kamba, V. Bovtun, J. Pokorný, M. Savinov, V. Porokhonskyy, D. Rafaja, P. Vaněk, A. Almeida, M. R. Chaves, A. A. Volkov, M. Dressel, and R. Waser, “Dielectric, infrared, and Raman response of doped SrTiO3 ceramics: Evidence of polar grain boundaries,” Phys. Rev. B 64(18), 184111 (2001).
[Crossref]

Zenhausern, F.

F. Zenhausern, Y. Martin, and H. K. Wickramasinghe, “Scanning Interferometric Apertureless Microscopy: Optical Imaging at 10 Angstrom Resolution,” Science 269(5227), 1083–1085 (1995).
[Crossref]

Zenobi, R.

J. Stadler, T. Schmid, and R. Zenobi, “Developments in and practical guidelines for tip-enhanced Raman spectroscopy,” Nanoscale 4(6), 1856–1870 (2012).
[Crossref]

Zerweck, U.

M. P. Nikiforov, S. C. Kehr, T. Park, P. Milde, U. Zerweck, C. Loppacher, L. M. Eng, M. J. Therien, N. Engheta, and D. Bonnell, “Probing polarization and dielectric function of molecules with higher order harmonics in scattering–near-field scanning optical microscopy,” J. Appl. Phys. 106(11), 114307 (2009).
[Crossref]

Zhang, X.

L. Wehmeier, D. Lang, Y. Liu, X. Zhang, S. Winnerl, L. M. Eng, and S. C. Kehr, “Polarization-dependent near-field phonon nanoscopy of oxides: SrTiO3, LiNbO3, and PbZr0.2Ti0.8O3,” Phys. Rev. B 100(3), 035444 (2019).
[Crossref]

Ziegler, A.

A. J. Huber, A. Ziegler, T. Köck, and R. Hillenbrand, “Infrared nanoscopy of strained semiconductors,” Nat. Nanotechnol. 4(3), 153–157 (2009).
[Crossref]

ACS Nano (1)

T. Mino, Y. Saito, and P. Verma, “Quantitative analysis of polarization-controlled tip-enhanced Raman imaging through the evaluation of the tip dipole,” ACS Nano 8(10), 10187–10195 (2014).
[Crossref]

ACS Photonics (2)

O. Khatib, H. A. Bechtel, M. C. Martin, M. B. Raschke, and G. Lawrence Carr, “Far infrared synchrotron near-field nanoimaging and nanospectroscopy,” ACS Photonics 5(7), 2773–2779 (2018).
[Crossref]

C. Maissen, S. Chen, E. Nikulina, A. Govyadinov, and R. Hillenbrand, “Probes for Ultrasensitive THz Nanoscopy,” ACS Photonics 6(5), 1279–1288 (2019).
[Crossref]

Adv. Funct. Mater. (1)

M. Lewin, C. Baeumer, F. Gunkel, A. Schwedt, F. Gaussmann, J. Wueppen, P. Meuffels, B. Jungbluth, J. Mayer, R. Dittmann, R. Waser, and T. Taubner, “Nanospectroscopy of Infrared Phonon Resonance Enables Local Quantification of Electronic Properties in Doped SrTiO3 Ceramics,” Adv. Funct. Mater. 28(42), 1802834 (2018).
[Crossref]

Appl. Phys. Lett. (3)

L. Wehmeier, T. Nörenberg, T. V. A. G. de Oliveira, J. M. Klopf, S. Y. Yang, L. W. Martin, R. Ramesh, L. M. Eng, and S. C. Kehr, “Phonon-induced near-field resonances in multiferroic BiFeO3 thin films at infrared and THz wavelengths,” Appl. Phys. Lett. 116(7), 071103 (2020).
[Crossref]

S. Schneider, J. Seidel, S. Grafström, L. M. Eng, S. Winnerl, D. Stehr, and M. Helm, “Impact of optical in-plane anisotropy on near-field phonon polariton spectroscopy,” Appl. Phys. Lett. 90(14), 143101 (2007).
[Crossref]

F. Kuschewski, H.-G. von Ribbeck, J. Döring, S. Winnerl, L. M. Eng, and S. C. Kehr, “Narrow-band near-field nanoscopy in the spectral range from 1.3 to 8.5 THz,” Appl. Phys. Lett. 108(11), 113102 (2016).
[Crossref]

Chem. Soc. Rev. (2)

N. Mauser and A. Hartschuh, “Tip-enhanced near-field optical microscopy,” Chem. Soc. Rev. 43(4), 1248–1262 (2014).
[Crossref]

N. Mauser and A. Hartschuh, “Tip-enhanced near-field optical microscopy,” Chem. Soc. Rev. 43(4), 1248–1262 (2014).
[Crossref]

J. Am. Chem. Soc. (1)

L. F. Lee, A. Adronov, R. D. Schaller, J. M. J. Fréchet, and R. J. Saykally, “Intermolecular Coupling in Nanometric Domains of Light-Harvesting Dendrimer Films Studied by Photoluminescence Near-Field Scanning Optical Microscopy (PL NSOM) “,” J. Am. Chem. Soc. 125(2), 536–540 (2003).
[Crossref]

J. Appl. Phys. (1)

M. P. Nikiforov, S. C. Kehr, T. Park, P. Milde, U. Zerweck, C. Loppacher, L. M. Eng, M. J. Therien, N. Engheta, and D. Bonnell, “Probing polarization and dielectric function of molecules with higher order harmonics in scattering–near-field scanning optical microscopy,” J. Appl. Phys. 106(11), 114307 (2009).
[Crossref]

J. Infrared, Millimeter, Terahertz Waves (1)

F. Keilmann, A. J. Huber, and R. Hillenbrand, “Nanoscale Conductivity Contrast by Scattering-Type Near-Field Optical Microscopy in the Visible, Infrared and THz Domains,” J. Infrared, Millimeter, Terahertz Waves 30, 1255–1268 (2009).
[Crossref]

J. Microsc. (3)

R. Hillenbrand, B. Knoll, and F. Keilmann, “Pure optical contrast in scattering-type scanning near-field microscopy,” J. Microsc. 202(1), 77–83 (2001).
[Crossref]

T. Taubner, R. Hillenbrand, and F. Keilmann, “Performance of visible and mid-infrared scattering-type near-field optical microscopes,” J. Microsc. 210(3), 311–314 (2003).
[Crossref]

A. J. Huber, N. Ocelic, and R. Hillenbrand, “Local excitation and interference of surface phonon polaritons studied by near-field infrared microscopy,” J. Microsc. 229(3), 389–395 (2008).
[Crossref]

J. Opt. Soc. Am. A (1)

J. Phys. Chem. Lett. (3)

Y. Saito and P. Verma, “Polarization-controlled Raman microscopy and nanoscopy,” J. Phys. Chem. Lett. 3(10), 1295–1300 (2012).
[Crossref]

M. D. Sonntag, E. A. Pozzi, N. Jiang, M. C. Hersam, and R. P. Van Duyne, “Recent advances in tip-enhanced Raman spectroscopy,” J. Phys. Chem. Lett. 5(18), 3125–3130 (2014).
[Crossref]

S. Berweger, J. M. Atkin, R. L. Olmon, and M. B. Raschke, “Light on the tip of a needle: Plasmonic nanofocusing for spectroscopy on the nanoscale,” J. Phys. Chem. Lett. 3(7), 945–952 (2012).
[Crossref]

J. Raman Spectrosc. (3)

R. H. Rickman and P. R. Dunstan, “Enhancement of lattice defect signatures in graphene and ultrathin graphite using tip-enhanced Raman spectroscopy,” J. Raman Spectrosc. 45(1), 15–21 (2014).
[Crossref]

S. Berweger and M. B. Raschke, “Polar Phonon Mode Selection. Rules in Tip-Enhanced Raman Scattering,” J. Raman Spectrosc. 40(10), 1413–1419 (2009).
[Crossref]

T. Mino, Y. Saito, H. Yoshida, S. Kawata, and P. Verma, “Molecular orientation analysis of organic thin films by z-polarization Raman microscope,” J. Raman Spectrosc. 43(12), 2029–2034 (2012).
[Crossref]

Laser Photonics Rev. (1)

P. Verma, T. Ichimura, T. Yano, Y. Saito, and S. Kawata, “Nano-imaging through tip-enhanced Raman spectroscopy: Stepping beyond the classical limits,” Laser Photonics Rev. 4(4), 548–561 (2010).
[Crossref]

Nano Lett. (5)

M. Brehm, T. Taubner, R. Hillenbrand, and F. Keilmann, “Infrared Spectroscopic Mapping of Single Nanoparticles and Viruses at Nanoscale Resolution,” Nano Lett. 6(7), 1307–1310 (2006).
[Crossref]

K.-D. Park and M. B. Raschke, “Polarization control with plasmonic antenna-tips: A universal approach for optical nano-crystallography and vector-field imaging,” Nano Lett. 18(5), 2912–2917 (2018).
[Crossref]

F. Huth, A. Govyadinov, S. Amarie, W. Nuansing, F. Keilmann, and R. Hillenbrand, “Nano-FTIR Absorption Spectroscopy of Molecular Fingerprints at 20 nm Spatial Resolution,” Nano Lett. 12(8), 3973–3978 (2012).
[Crossref]

A. J. Huber, F. Keilmann, J. Wittborn, J. Aizpurua, and R. Hillenbrand, “Terahertz near-field nanoscopy of mobile carriers in single semiconductor nanodevices,” Nano Lett. 8(11), 3766–3770 (2008).
[Crossref]

T. Taubner, F. Keilmann, and R. Hillenbrand, “Nanomechanical resonance tuning and phase effects in optical near-field interaction,” Nano Lett. 4(9), 1669–1672 (2004).
[Crossref]

Nanoscale (1)

J. Stadler, T. Schmid, and R. Zenobi, “Developments in and practical guidelines for tip-enhanced Raman spectroscopy,” Nanoscale 4(6), 1856–1870 (2012).
[Crossref]

Nanotechnology (2)

R. Beams, L. G. Cancado, A. Jorio, A. N. Vamivakas, and L. Novotny, “Tip-enhanced Raman mapping of local strain in graphene,” Nanotechnology 26(17), 175702 (2015).
[Crossref]

A. J. Huber, J. Wittborn, and R. Hillenbrand, “Infrared spectroscopic near-field mapping of single nanotransistors,” Nanotechnology 21(23), 235702 (2010).
[Crossref]

Nat. Commun. (1)

P. Alonso-González, P. Albella, M. Schnell, J. Chen, F. Huth, A. García-Etxarri, F. Casanova, F. Golmar, L. Arzubiaga, L. E. Hueso, J. Aizpurua, and R. Hillenbrand, “Resolving the electromagnetic mechanism of surface-enhanced light scattering at single hot spots,” Nat. Commun. 3(1), 684 (2012).
[Crossref]

Nat. Mater. (1)

P. Li, X. Yang, T. W. Maß, J. Hanss, M. Lewin, A. K. U. Michel, M. Wuttig, and T. Taubner, “Reversible optical switching of highly confined phonon–polaritons with an ultrathin phase-change material,” Nat. Mater. 15(8), 870–875 (2016).
[Crossref]

Nat. Nanotechnol. (1)

A. J. Huber, A. Ziegler, T. Köck, and R. Hillenbrand, “Infrared nanoscopy of strained semiconductors,” Nat. Nanotechnol. 4(3), 153–157 (2009).
[Crossref]

Nat. Photonics (1)

N. Rotenberg and L. Kuipers, “Mapping nanoscale light fields,” Nat. Photonics 8(12), 919–926 (2014).
[Crossref]

Nature (2)

R. Hillenbrand, T. Taubner, and F. Keilmann, “Phonon-enhanced light–matter interaction at the nanometre scale,” Nature 418(6894), 159–162 (2002).
[Crossref]

B. Knoll and F. Keilmann, “Scanning microscopy by mid-infrared near-field scattering,” Nature 399(6732), 134–137 (1999).
[Crossref]

Opt. Commun. (1)

B. Knoll and F. Keilmann, “Enhanced dielectric contrast in scattering-type scanning near-field optical microscopy,” Opt. Commun. 182(4-6), 321–328 (2000).
[Crossref]

Opt. Express (4)

Phys. Rev. B (5)

L. Wehmeier, D. Lang, Y. Liu, X. Zhang, S. Winnerl, L. M. Eng, and S. C. Kehr, “Polarization-dependent near-field phonon nanoscopy of oxides: SrTiO3, LiNbO3, and PbZr0.2Ti0.8O3,” Phys. Rev. B 100(3), 035444 (2019).
[Crossref]

J. Renger, S. Grafström, L. M. Eng, and R. Hillenbrand, “Resonant light scattering by near-field-induced phonon polaritons,” Phys. Rev. B 71(7), 075410 (2005).
[Crossref]

J. Petzelt, T. Ostapchuk, I. Gregora, I. Rychetský, S. Hoffmann-Eifert, A. V. Pronin, Y. Yuzyuk, B. P. Gorshunov, S. Kamba, V. Bovtun, J. Pokorný, M. Savinov, V. Porokhonskyy, D. Rafaja, P. Vaněk, A. Almeida, M. R. Chaves, A. A. Volkov, M. Dressel, and R. Waser, “Dielectric, infrared, and Raman response of doped SrTiO3 ceramics: Evidence of polar grain boundaries,” Phys. Rev. B 64(18), 184111 (2001).
[Crossref]

R. L. Olmon, B. Slovick, T. W. Johnson, D. Shelton, S. -H. Oh, G. D. Boreman, and M. B. Raschke, “Optical dielectric function of gold,” Phys. Rev. B 86, 235147 (2012).
[Crossref]

A. S. McLeod, P. Kelly, M. D. Goldflam, Z. Gainsforth, A. J. Westphal, G. Dominguez, M. H. Thiemens, M. M. Fogler, and D. N. Basov, “Model for quantitative tip-enhanced spectroscopy and the extraction of nanoscale-resolved optical constants,” Phys. Rev. B 90(8), 085136 (2014).
[Crossref]

Phys. Rev. Lett. (4)

S. C. Kehr, M. Cebula, O. Mieth, T. Härtling, J. Seidel, S. Grafström, L. M. Eng, S. Winnerl, D. Stehr, and M. Helm, “Anisotropy Contrast in Phonon-Enhanced Apertureless Near-Field Microscopy Using a Free-Electron Laser,” Phys. Rev. Lett. 100(25), 256403 (2008).
[Crossref]

M. I. Stockman, “Nanofocusing of optical energy in tapered plasmonic waveguides,” Phys. Rev. Lett. 93(13), 137404 (2004).
[Crossref]

R. L. Olmon, M. Rang, P. M. Krenz, B. A. Lail, L. V. Saraf, G. D. Boreman, and M. B. Raschke, “Determination of electric-field, magnetic-field, and electric-current distributions of infrared optical antennas: A near-field optical vector network analyser,” Phys. Rev. Lett. 105(16), 167403 (2010).
[Crossref]

P. Anger, P. Bharadwaj, and L. Novotny, “Enhancement and quenching of single-molecule fluorescence,” Phys. Rev. Lett. 96(11), 113002 (2006).
[Crossref]

Phys. Rev. Res. (1)

P. McArdle, D. J. Lahneman, A. Biswas, F. Keilmann, and M. M. Qazilbash, “Near-field infrared nanospectroscopy of sur-face phonon-polariton resonances,” Phys. Rev. Res. 2(2), 023272 (2020).
[Crossref]

Rev. Sci. Instrum. (1)

M. Esslinger, J. Dorfmüller, W. Khunsin, R. Vogelgesang, and K. Kern, “Background-free imaging of plasmonic structures with cross-polarized apertureless scanning near-field optical microscopy,” Rev. Sci. Instrum. 83(3), 033704 (2012).
[Crossref]

Sci. Rep. (1)

A. Ghimire, E. Shafran, and J. M. Gerton, “Using a sharp metal tip to control the polarization and direction of emission from a quantum dot,” Sci. Rep. 4(1), 6456 (2015).
[Crossref]

Science (1)

F. Zenhausern, Y. Martin, and H. K. Wickramasinghe, “Scanning Interferometric Apertureless Microscopy: Optical Imaging at 10 Angstrom Resolution,” Science 269(5227), 1083–1085 (1995).
[Crossref]

Small (1)

R. Eckel, V. Walhorn, C. Pelargus, J. Martini, J. Enderlein, T. Nann, D. Anselmetti, and R. Ros, “Fluorescence-emission control of single CdSe nanocrystals using gold-modified AFM tips,” Small 3(1), 44–49 (2007).
[Crossref]

Sync. Rad. News (1)

S. C. Kehr, J. Döring, M. Gensch, M. Helm, and L. M. Eng, “FEL-Based Near-Field Infrared to THz Nanoscopy,” Sync. Rad. News 30(4), 31–35 (2017).
[Crossref]

Other (1)

C. F. Bohren and D. R. Huffman, “Absorption and Scattering of Light by Small Particles,” WILEY-VCH Verlag GmbH & Co. KGaA, DOI:10.1002/9783527618156 (1998).

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Figures (7)

Fig. 1.
Fig. 1. Comparison of the field distributions at the sample surface for the four configurations of near-field coupled systems (rows) including a spherical tip (radius a = 5 nm) at a tip-sample separation of h0=1 nm and an extended sample for p- and s-polarized excitation (columns). For each case 1 - 4, the vector field distribution is shown along with the extracted values for every field component E||,x, E||,y, and E⊥,z. Notably, the fields on the sample surface have very different characteristics: For p-polarization, the field distribution is dominated by the z-component with a maximum located at x = 0 (underneath the tip). On the other hand, for s-polarization, maxima for E⊥,z are observed at y ≠ 0, while for resonant excitation a dominant in-plane contribution is found at y = 0.
Fig. 2.
Fig. 2. Schematic setup of the near-field-coupled tip-sample s-SNOM system, utilized for both analytical calculations and modelling. If not stated otherwise, we assume the following parameters: tip apex radius a = 5 nm, tip-sample distance ${h_0}$=1 nm, illumination with p- or s-polarized light that impinges at an angle of θ = 45°, as well as complex permittivities ${{\varepsilon }_{\textrm{tip}}}$,${\varepsilon _s}$, and ${{\varepsilon }_\textrm{m}}$ for tip, sample, and surrounding medium (air), respectively.
Fig. 3.
Fig. 3. Local electric field strength plotted as a function of the real parts of tip (x-axes) and sample permittivity (y-axes), as calculated via the analytic dipole model within the ± 15 interval: (a) perpendicular (out-of-plane) field component; (b) parallel (in-plane) field orientation. Note that imaginary parts are fixed at 0.1, and the tip with radius a = 5 nm is approached to ho = 1 nm to the sample surface. Notably, two branches of near-field enhancement (brighter colors) are observed for both field components used, corresponding to tip- (area 2) and sample- (area 3) related resonances. Strongest enhancement of the local fields is found for double resonant excitation (area 4) reaching values of up to 315 and 52 for (a) perpendicular ($\bot )$ and (b) parallel (||) field orientation, respectively.
Fig. 4.
Fig. 4. Local vector field distributions for case 1 when using non-resonant Au for both tip and sample in the mid-IR wavelength regime, plotted for (a) p- and (b) s-polarized incident light. (c,d) display the total electric fields underneath the tip as a function of tip-sample distance h0 (varied from 1 - 5 nm) and wavelength λ (spectral range from 13.5–16 µm), when using (c) p- and (d) s-polarized incident light. A spectrally flat near-field is found that characteristically decays vs. distance h0. Largest field enhancements of 15.4 are found for p-polarized light at h0 =1nm, whereas for s-polarized light, the field at the sample surface is negligibly small (factor of 1 × 10−6). As expected from a good metal, the vector field on the sample surface has z-components, only.
Fig. 5.
Fig. 5. Local vector field distribution for resonant tip (STO) and non-resonant sample (Au), illustrated for (a) p- and (b) s-polarized incident light. (c,d) show the electric field strength at the sample surface underneath the tip as a function of tip-sample distance h0  and wavelength λ for (c) p- and (d) s-polarization. The local field enhancement on the sample surface reaches 41.7 and 0.00041 for p- and s-polarization at h0 =1nm, respectively (maxima marked by red circles for selected h0). The field penetrates the resonant tip with a strongly wavelength dependent behavior. The field inside the metallic sample is exactly zero, forming the boundary condition for strictly z-oriented field components at the sample surface.
Fig. 6.
Fig. 6. Local vector field distributions for non-resonant tip (Au) and resonant sample (STO), shown for (a) p- and (b) s-polarized incident light, respectively. (c,d) display field plots underneath the tip, as a function of tip-sample distance h0 and wavelength λ for (c) p- and (d) s-polarization (spectral maxima marked by red circles). Field enhancements of up to 25.9 and 1.74 are found for p- and s-polarization, respectively. The local fields penetrate the STO sample and show significant in-plane components both at the sample surface and within the sample, particularly for s-polarized excitation.
Fig. 7.
Fig. 7. Local vector field distribution for resonant tip and sample made up of STO, for both (a) p- and (b) s-polarized incident light. (c,d) display the local field underneath the tip as a function of tip-sample distance h0 and wavelength λ, for (c) p- and (d) s-polarization (spectral maxima marked by red circles). This double-resonant configuration enables the strongest local field enhancements of up to 79 and 3.4 for p- and s-polarized excitation, respectively, demonstrating clearly the significance of s-polarized components for resonant excitation.

Tables (1)

Tables Icon

Table 1. Comparison of the four configurations of near-field coupled systems at a h0 =1nm tip-sample separation. We calculate here ratios of field enhancements underneath the tip for both p- and s-polarized incident light, taking the non-resonant tip/sample excitation case 1 as the reference (i.e. Ep/Ep,non =1; Es/Es,non-res =1). Particularly for resonant samples (cases 3 and 4), the local fields for s-polarized excitation are strongly enhanced, reaching significant values on the same order of magnitude as for non-resonant p-polarized excitation, but more than 5 orders of magnitude stronger as compared to the non-resonant s-polarized case.

Equations (1)

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E Local = α t 4 π h 3 ( β 1 1 α t β 32 π h 3 . E x 0 β 1 1 α t β 32 π h 3 . E y 0 2 ( β + 1 ) 1 α t β 16 π h 3 . E z 0 ) .

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