Abstract

We report illumination-mode near-field optical microscopy images of individual 80–115-nm-diameter Au particles recorded with metal-coated fiber probes. It is found that the images are strongly influenced by the metal-coating thickness. This dependence is consistent with theoretical models, which are in good agreement with the experimental images. Probes with thick coatings (∼λ/2) produce images consisting of three extrema, owing to a resonancelike polarization of the probe end. Probes with thinner coatings generally produce simpler images. However, in some cases the images contain wavelike structures that are due to interference between direct radiation from the tip and propagating tip fields scattered by the particles.

© 1999 Optical Society of America

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  1. N. van Hulst, A. Lewis, eds., Proceedings of the 4th International Conference on Near-Field Optics, Jerusalem, Israel, 9–13 February 1997; Ultramicroscopy 71 (1998).
  2. B. Hecht, H. Bielefeldt, Y. Inouye, D. W. Pohl, L. Novotny, “Facts and artifacts in near-field optical microscopy,” J. Appl. Phys. 81, 2492–2498 (1997).
    [CrossRef]
  3. See R. Carminati, A. Madrazo, M. Nieto-Vesperinas, J.-J. Greffet, “Optical content and resolution of near-field optical images: influence of the operating mode,” J. Appl. Phys. 82, 501–509 (1997);S. I. Bozhevolnyi, “Topographical artifacts and optical resolution in near-field optical microscopy,” J. Opt. Soc. Am. B 14, 2254–2259 (1997);C. Girard, D. Courjon, “The role of scanning mode in near-field optical microscopy,” Surf. Sci. 382, 9–18 (1997), and references therein.
    [CrossRef]
  4. V. Sandoghdar, S. Wegscheider, G. Krausch, J. Mlynek, “Reflection scanning near-field optical microscopy with uncoated fiber tips: how good is the resolution really?” J. Appl. Phys. 81, 2499–2503 (1997).
    [CrossRef]
  5. E. Betzig, R. J. Chichester, “Single molecules observed by near-field scanning optical microscopy,” Science 262, 1422–1425 (1993);E. Betzig, J. K. Trautman, T. D. Harris, J. S. Weiner, R. L. Kostelak, “Breaking the diffraction barrier—optical microscopy on a nanometric scale,” Science 251, 1468–1470 (1991).
    [CrossRef] [PubMed]
  6. H. A. Bethe, “Theory of diffraction by small holes,” Phys. Rev. 66, 163–182 (1944);C. J. Bouwkamp, “On Bethe’s theory of diffraction by small holes,” Philips Res. Rep. 5, 321–332 (1950); “On the diffraction of electromagnetic waves by small circular disks and holes,” 5, 401–422 (1950).
    [CrossRef]
  7. S. J. Stranick, L. J. Richter, R. R. Cavanagh, “High efficiency, dual collection mode near-field scanning optical microscope,” J. Vac. Sci. Technol. B 16, 1948–1952 (1998).
    [CrossRef]
  8. C. E. Jordan, S. J. Stranick, L. J. Richter, R. R. Cavanagh, “Removing optical artifacts in near-field scanning optical microscopy by using a three dimensional scanning mode,” J. Appl. Phys (to be published).
  9. Certain commercial equipment, instruments, or materials are identified in this paper to specify adequately the experimental procedure. In no case does such identification imply recommendation or endorsement by the National Institute of Standards and Technology, nor does it imply that the equipment or the materials identified are necessarily the best available for the purpose.
  10. K. R. Brown, M. J. Natan, “Hydroxylamine seeding of colloidal Au nanoparticles in solution and on surfaces,” Langmuir 14, 726–728 (1998);K. R. Brown, D. G. Walter, M. J. Natan, “Seeding of colloidal Au nanoparticles in solution. II. Improved control of particle size and shape,” submitted to Chem. Mater.
    [CrossRef]
  11. R. G. Freeman, K. C. Grabar, A. P. Guthrie, K. J. Allison, R. M. Bright, J. A. Davis, M. B. Hommer, M. A. Jackson, P. C. Smith, D. G. Walter, M. J. Natan, “Self-assembled metal colloid monolayers—an approach to SERS substrates,” Science 267, 1629–1632 (1995);K. C. Grabar, R. G. Freeman, M. B. Hommer, M. J. Natan, “Preparation and characterization of Au colloid monolayers,” Anal. Chem. 67, 735–743 (1995);K. G. Grabar, K. J. Allison, B. E. Baker, R. M. Bright, K. R. Brown, C. D. Keating, R. G. Freeman, A. P. Fox, M. D. Musick, M. J. Natan, “Two-dimensional arrays of colloidal gold particles: a flexible approach to macroscopic metal surfaces,” Langmuir 12, 2353–2361 (1996).
    [CrossRef] [PubMed]
  12. Adjustments of ±30% of a typical dither drive amplitude ±3% off the tip resonance frequency and minimizing the shear-force damping are common optimization routes after tip exchange.
  13. The deposition rate reported is for a rotating sample/tip. A tooling factor accounts for both the rotation and the position of microbalance relative to the sample. The reported film thicknesses are referenced through the tooling factor to the measured film thickness on slides coated in the nominal tip position.
  14. E. Betzig, J. K. Trautman, “Near-field optics—microscopy, spectroscopy, and surface modification beyond the diffraction limit,” Science 257, 189–195 (1992);G. A. Valaskovic, M. Holton, G. H. Morrison, “Parameter control, characterization, and optimization in the fabrication of optical-fiber near-field probes,” Appl. Opt. 34, 1215–1228 (1995).
    [CrossRef] [PubMed]
  15. Although unlikely, it is possible that the metal coating and the glass face lie exactly in the same plane, resulting in no topographic contrast for the aperture.
  16. Small sample features will provide the highest-fidelity images of the probe.
  17. No attempt was made to deconvolve the sample asperity responsible for the topographic contrast. Thus the tabulated base width is an upper limit on the true width of the probe, and the tabulated aperture ID is a lower limit on the true aperture ID.
  18. Information about the model is available from A. Liu, G. W. Bryant, L. J. Richter, S. J. Stranick, National Institute of Standards and Technology, Gaithersburg, Maryland 20899.
  19. B. T. Draine, P. J. Flatau, “Discrete-dipole approximation for scattering calculations,” J. Opt. Soc. Am. A 11, 1491–1499 (1994).
    [CrossRef]
  20. S. B. Singham, C. F. Bohren, “Light-scattering by an arbitrary particle—the scattering-order formulation of the coupled-dipole method,” J. Opt. Soc. Am. A 5, 1867–1872 (1988).
    [CrossRef] [PubMed]
  21. We note that the three-extrema structure cannot be attributed to the weak oscillations in the calculated Y line scans for thin coatings in Fig. 9. The calculated separation between the first maxima in the Y line scans is much larger than observed (∼700 nm), and the calculated maxima appear along the wide dimension of the central minimum, not as observed along the narrow dimension.
  22. C. Obermüller, K. Karrai, “Far field characterization of diffracting circular apertures,” Appl. Phys. Lett. 67, 3408–3410 (1995).
    [CrossRef]

1998 (2)

S. J. Stranick, L. J. Richter, R. R. Cavanagh, “High efficiency, dual collection mode near-field scanning optical microscope,” J. Vac. Sci. Technol. B 16, 1948–1952 (1998).
[CrossRef]

K. R. Brown, M. J. Natan, “Hydroxylamine seeding of colloidal Au nanoparticles in solution and on surfaces,” Langmuir 14, 726–728 (1998);K. R. Brown, D. G. Walter, M. J. Natan, “Seeding of colloidal Au nanoparticles in solution. II. Improved control of particle size and shape,” submitted to Chem. Mater.
[CrossRef]

1997 (3)

B. Hecht, H. Bielefeldt, Y. Inouye, D. W. Pohl, L. Novotny, “Facts and artifacts in near-field optical microscopy,” J. Appl. Phys. 81, 2492–2498 (1997).
[CrossRef]

See R. Carminati, A. Madrazo, M. Nieto-Vesperinas, J.-J. Greffet, “Optical content and resolution of near-field optical images: influence of the operating mode,” J. Appl. Phys. 82, 501–509 (1997);S. I. Bozhevolnyi, “Topographical artifacts and optical resolution in near-field optical microscopy,” J. Opt. Soc. Am. B 14, 2254–2259 (1997);C. Girard, D. Courjon, “The role of scanning mode in near-field optical microscopy,” Surf. Sci. 382, 9–18 (1997), and references therein.
[CrossRef]

V. Sandoghdar, S. Wegscheider, G. Krausch, J. Mlynek, “Reflection scanning near-field optical microscopy with uncoated fiber tips: how good is the resolution really?” J. Appl. Phys. 81, 2499–2503 (1997).
[CrossRef]

1995 (2)

R. G. Freeman, K. C. Grabar, A. P. Guthrie, K. J. Allison, R. M. Bright, J. A. Davis, M. B. Hommer, M. A. Jackson, P. C. Smith, D. G. Walter, M. J. Natan, “Self-assembled metal colloid monolayers—an approach to SERS substrates,” Science 267, 1629–1632 (1995);K. C. Grabar, R. G. Freeman, M. B. Hommer, M. J. Natan, “Preparation and characterization of Au colloid monolayers,” Anal. Chem. 67, 735–743 (1995);K. G. Grabar, K. J. Allison, B. E. Baker, R. M. Bright, K. R. Brown, C. D. Keating, R. G. Freeman, A. P. Fox, M. D. Musick, M. J. Natan, “Two-dimensional arrays of colloidal gold particles: a flexible approach to macroscopic metal surfaces,” Langmuir 12, 2353–2361 (1996).
[CrossRef] [PubMed]

C. Obermüller, K. Karrai, “Far field characterization of diffracting circular apertures,” Appl. Phys. Lett. 67, 3408–3410 (1995).
[CrossRef]

1994 (1)

1993 (1)

E. Betzig, R. J. Chichester, “Single molecules observed by near-field scanning optical microscopy,” Science 262, 1422–1425 (1993);E. Betzig, J. K. Trautman, T. D. Harris, J. S. Weiner, R. L. Kostelak, “Breaking the diffraction barrier—optical microscopy on a nanometric scale,” Science 251, 1468–1470 (1991).
[CrossRef] [PubMed]

1992 (1)

E. Betzig, J. K. Trautman, “Near-field optics—microscopy, spectroscopy, and surface modification beyond the diffraction limit,” Science 257, 189–195 (1992);G. A. Valaskovic, M. Holton, G. H. Morrison, “Parameter control, characterization, and optimization in the fabrication of optical-fiber near-field probes,” Appl. Opt. 34, 1215–1228 (1995).
[CrossRef] [PubMed]

1988 (1)

1944 (1)

H. A. Bethe, “Theory of diffraction by small holes,” Phys. Rev. 66, 163–182 (1944);C. J. Bouwkamp, “On Bethe’s theory of diffraction by small holes,” Philips Res. Rep. 5, 321–332 (1950); “On the diffraction of electromagnetic waves by small circular disks and holes,” 5, 401–422 (1950).
[CrossRef]

Allison, K. J.

R. G. Freeman, K. C. Grabar, A. P. Guthrie, K. J. Allison, R. M. Bright, J. A. Davis, M. B. Hommer, M. A. Jackson, P. C. Smith, D. G. Walter, M. J. Natan, “Self-assembled metal colloid monolayers—an approach to SERS substrates,” Science 267, 1629–1632 (1995);K. C. Grabar, R. G. Freeman, M. B. Hommer, M. J. Natan, “Preparation and characterization of Au colloid monolayers,” Anal. Chem. 67, 735–743 (1995);K. G. Grabar, K. J. Allison, B. E. Baker, R. M. Bright, K. R. Brown, C. D. Keating, R. G. Freeman, A. P. Fox, M. D. Musick, M. J. Natan, “Two-dimensional arrays of colloidal gold particles: a flexible approach to macroscopic metal surfaces,” Langmuir 12, 2353–2361 (1996).
[CrossRef] [PubMed]

Bethe, H. A.

H. A. Bethe, “Theory of diffraction by small holes,” Phys. Rev. 66, 163–182 (1944);C. J. Bouwkamp, “On Bethe’s theory of diffraction by small holes,” Philips Res. Rep. 5, 321–332 (1950); “On the diffraction of electromagnetic waves by small circular disks and holes,” 5, 401–422 (1950).
[CrossRef]

Betzig, E.

E. Betzig, R. J. Chichester, “Single molecules observed by near-field scanning optical microscopy,” Science 262, 1422–1425 (1993);E. Betzig, J. K. Trautman, T. D. Harris, J. S. Weiner, R. L. Kostelak, “Breaking the diffraction barrier—optical microscopy on a nanometric scale,” Science 251, 1468–1470 (1991).
[CrossRef] [PubMed]

E. Betzig, J. K. Trautman, “Near-field optics—microscopy, spectroscopy, and surface modification beyond the diffraction limit,” Science 257, 189–195 (1992);G. A. Valaskovic, M. Holton, G. H. Morrison, “Parameter control, characterization, and optimization in the fabrication of optical-fiber near-field probes,” Appl. Opt. 34, 1215–1228 (1995).
[CrossRef] [PubMed]

Bielefeldt, H.

B. Hecht, H. Bielefeldt, Y. Inouye, D. W. Pohl, L. Novotny, “Facts and artifacts in near-field optical microscopy,” J. Appl. Phys. 81, 2492–2498 (1997).
[CrossRef]

Bohren, C. F.

Bright, R. M.

R. G. Freeman, K. C. Grabar, A. P. Guthrie, K. J. Allison, R. M. Bright, J. A. Davis, M. B. Hommer, M. A. Jackson, P. C. Smith, D. G. Walter, M. J. Natan, “Self-assembled metal colloid monolayers—an approach to SERS substrates,” Science 267, 1629–1632 (1995);K. C. Grabar, R. G. Freeman, M. B. Hommer, M. J. Natan, “Preparation and characterization of Au colloid monolayers,” Anal. Chem. 67, 735–743 (1995);K. G. Grabar, K. J. Allison, B. E. Baker, R. M. Bright, K. R. Brown, C. D. Keating, R. G. Freeman, A. P. Fox, M. D. Musick, M. J. Natan, “Two-dimensional arrays of colloidal gold particles: a flexible approach to macroscopic metal surfaces,” Langmuir 12, 2353–2361 (1996).
[CrossRef] [PubMed]

Brown, K. R.

K. R. Brown, M. J. Natan, “Hydroxylamine seeding of colloidal Au nanoparticles in solution and on surfaces,” Langmuir 14, 726–728 (1998);K. R. Brown, D. G. Walter, M. J. Natan, “Seeding of colloidal Au nanoparticles in solution. II. Improved control of particle size and shape,” submitted to Chem. Mater.
[CrossRef]

Bryant, G. W.

Information about the model is available from A. Liu, G. W. Bryant, L. J. Richter, S. J. Stranick, National Institute of Standards and Technology, Gaithersburg, Maryland 20899.

Carminati, R.

See R. Carminati, A. Madrazo, M. Nieto-Vesperinas, J.-J. Greffet, “Optical content and resolution of near-field optical images: influence of the operating mode,” J. Appl. Phys. 82, 501–509 (1997);S. I. Bozhevolnyi, “Topographical artifacts and optical resolution in near-field optical microscopy,” J. Opt. Soc. Am. B 14, 2254–2259 (1997);C. Girard, D. Courjon, “The role of scanning mode in near-field optical microscopy,” Surf. Sci. 382, 9–18 (1997), and references therein.
[CrossRef]

Cavanagh, R. R.

S. J. Stranick, L. J. Richter, R. R. Cavanagh, “High efficiency, dual collection mode near-field scanning optical microscope,” J. Vac. Sci. Technol. B 16, 1948–1952 (1998).
[CrossRef]

C. E. Jordan, S. J. Stranick, L. J. Richter, R. R. Cavanagh, “Removing optical artifacts in near-field scanning optical microscopy by using a three dimensional scanning mode,” J. Appl. Phys (to be published).

Chichester, R. J.

E. Betzig, R. J. Chichester, “Single molecules observed by near-field scanning optical microscopy,” Science 262, 1422–1425 (1993);E. Betzig, J. K. Trautman, T. D. Harris, J. S. Weiner, R. L. Kostelak, “Breaking the diffraction barrier—optical microscopy on a nanometric scale,” Science 251, 1468–1470 (1991).
[CrossRef] [PubMed]

Davis, J. A.

R. G. Freeman, K. C. Grabar, A. P. Guthrie, K. J. Allison, R. M. Bright, J. A. Davis, M. B. Hommer, M. A. Jackson, P. C. Smith, D. G. Walter, M. J. Natan, “Self-assembled metal colloid monolayers—an approach to SERS substrates,” Science 267, 1629–1632 (1995);K. C. Grabar, R. G. Freeman, M. B. Hommer, M. J. Natan, “Preparation and characterization of Au colloid monolayers,” Anal. Chem. 67, 735–743 (1995);K. G. Grabar, K. J. Allison, B. E. Baker, R. M. Bright, K. R. Brown, C. D. Keating, R. G. Freeman, A. P. Fox, M. D. Musick, M. J. Natan, “Two-dimensional arrays of colloidal gold particles: a flexible approach to macroscopic metal surfaces,” Langmuir 12, 2353–2361 (1996).
[CrossRef] [PubMed]

Draine, B. T.

Flatau, P. J.

Freeman, R. G.

R. G. Freeman, K. C. Grabar, A. P. Guthrie, K. J. Allison, R. M. Bright, J. A. Davis, M. B. Hommer, M. A. Jackson, P. C. Smith, D. G. Walter, M. J. Natan, “Self-assembled metal colloid monolayers—an approach to SERS substrates,” Science 267, 1629–1632 (1995);K. C. Grabar, R. G. Freeman, M. B. Hommer, M. J. Natan, “Preparation and characterization of Au colloid monolayers,” Anal. Chem. 67, 735–743 (1995);K. G. Grabar, K. J. Allison, B. E. Baker, R. M. Bright, K. R. Brown, C. D. Keating, R. G. Freeman, A. P. Fox, M. D. Musick, M. J. Natan, “Two-dimensional arrays of colloidal gold particles: a flexible approach to macroscopic metal surfaces,” Langmuir 12, 2353–2361 (1996).
[CrossRef] [PubMed]

Grabar, K. C.

R. G. Freeman, K. C. Grabar, A. P. Guthrie, K. J. Allison, R. M. Bright, J. A. Davis, M. B. Hommer, M. A. Jackson, P. C. Smith, D. G. Walter, M. J. Natan, “Self-assembled metal colloid monolayers—an approach to SERS substrates,” Science 267, 1629–1632 (1995);K. C. Grabar, R. G. Freeman, M. B. Hommer, M. J. Natan, “Preparation and characterization of Au colloid monolayers,” Anal. Chem. 67, 735–743 (1995);K. G. Grabar, K. J. Allison, B. E. Baker, R. M. Bright, K. R. Brown, C. D. Keating, R. G. Freeman, A. P. Fox, M. D. Musick, M. J. Natan, “Two-dimensional arrays of colloidal gold particles: a flexible approach to macroscopic metal surfaces,” Langmuir 12, 2353–2361 (1996).
[CrossRef] [PubMed]

Greffet, J.-J.

See R. Carminati, A. Madrazo, M. Nieto-Vesperinas, J.-J. Greffet, “Optical content and resolution of near-field optical images: influence of the operating mode,” J. Appl. Phys. 82, 501–509 (1997);S. I. Bozhevolnyi, “Topographical artifacts and optical resolution in near-field optical microscopy,” J. Opt. Soc. Am. B 14, 2254–2259 (1997);C. Girard, D. Courjon, “The role of scanning mode in near-field optical microscopy,” Surf. Sci. 382, 9–18 (1997), and references therein.
[CrossRef]

Guthrie, A. P.

R. G. Freeman, K. C. Grabar, A. P. Guthrie, K. J. Allison, R. M. Bright, J. A. Davis, M. B. Hommer, M. A. Jackson, P. C. Smith, D. G. Walter, M. J. Natan, “Self-assembled metal colloid monolayers—an approach to SERS substrates,” Science 267, 1629–1632 (1995);K. C. Grabar, R. G. Freeman, M. B. Hommer, M. J. Natan, “Preparation and characterization of Au colloid monolayers,” Anal. Chem. 67, 735–743 (1995);K. G. Grabar, K. J. Allison, B. E. Baker, R. M. Bright, K. R. Brown, C. D. Keating, R. G. Freeman, A. P. Fox, M. D. Musick, M. J. Natan, “Two-dimensional arrays of colloidal gold particles: a flexible approach to macroscopic metal surfaces,” Langmuir 12, 2353–2361 (1996).
[CrossRef] [PubMed]

Hecht, B.

B. Hecht, H. Bielefeldt, Y. Inouye, D. W. Pohl, L. Novotny, “Facts and artifacts in near-field optical microscopy,” J. Appl. Phys. 81, 2492–2498 (1997).
[CrossRef]

Hommer, M. B.

R. G. Freeman, K. C. Grabar, A. P. Guthrie, K. J. Allison, R. M. Bright, J. A. Davis, M. B. Hommer, M. A. Jackson, P. C. Smith, D. G. Walter, M. J. Natan, “Self-assembled metal colloid monolayers—an approach to SERS substrates,” Science 267, 1629–1632 (1995);K. C. Grabar, R. G. Freeman, M. B. Hommer, M. J. Natan, “Preparation and characterization of Au colloid monolayers,” Anal. Chem. 67, 735–743 (1995);K. G. Grabar, K. J. Allison, B. E. Baker, R. M. Bright, K. R. Brown, C. D. Keating, R. G. Freeman, A. P. Fox, M. D. Musick, M. J. Natan, “Two-dimensional arrays of colloidal gold particles: a flexible approach to macroscopic metal surfaces,” Langmuir 12, 2353–2361 (1996).
[CrossRef] [PubMed]

Inouye, Y.

B. Hecht, H. Bielefeldt, Y. Inouye, D. W. Pohl, L. Novotny, “Facts and artifacts in near-field optical microscopy,” J. Appl. Phys. 81, 2492–2498 (1997).
[CrossRef]

Jackson, M. A.

R. G. Freeman, K. C. Grabar, A. P. Guthrie, K. J. Allison, R. M. Bright, J. A. Davis, M. B. Hommer, M. A. Jackson, P. C. Smith, D. G. Walter, M. J. Natan, “Self-assembled metal colloid monolayers—an approach to SERS substrates,” Science 267, 1629–1632 (1995);K. C. Grabar, R. G. Freeman, M. B. Hommer, M. J. Natan, “Preparation and characterization of Au colloid monolayers,” Anal. Chem. 67, 735–743 (1995);K. G. Grabar, K. J. Allison, B. E. Baker, R. M. Bright, K. R. Brown, C. D. Keating, R. G. Freeman, A. P. Fox, M. D. Musick, M. J. Natan, “Two-dimensional arrays of colloidal gold particles: a flexible approach to macroscopic metal surfaces,” Langmuir 12, 2353–2361 (1996).
[CrossRef] [PubMed]

Jordan, C. E.

C. E. Jordan, S. J. Stranick, L. J. Richter, R. R. Cavanagh, “Removing optical artifacts in near-field scanning optical microscopy by using a three dimensional scanning mode,” J. Appl. Phys (to be published).

Karrai, K.

C. Obermüller, K. Karrai, “Far field characterization of diffracting circular apertures,” Appl. Phys. Lett. 67, 3408–3410 (1995).
[CrossRef]

Krausch, G.

V. Sandoghdar, S. Wegscheider, G. Krausch, J. Mlynek, “Reflection scanning near-field optical microscopy with uncoated fiber tips: how good is the resolution really?” J. Appl. Phys. 81, 2499–2503 (1997).
[CrossRef]

Liu, A.

Information about the model is available from A. Liu, G. W. Bryant, L. J. Richter, S. J. Stranick, National Institute of Standards and Technology, Gaithersburg, Maryland 20899.

Madrazo, A.

See R. Carminati, A. Madrazo, M. Nieto-Vesperinas, J.-J. Greffet, “Optical content and resolution of near-field optical images: influence of the operating mode,” J. Appl. Phys. 82, 501–509 (1997);S. I. Bozhevolnyi, “Topographical artifacts and optical resolution in near-field optical microscopy,” J. Opt. Soc. Am. B 14, 2254–2259 (1997);C. Girard, D. Courjon, “The role of scanning mode in near-field optical microscopy,” Surf. Sci. 382, 9–18 (1997), and references therein.
[CrossRef]

Mlynek, J.

V. Sandoghdar, S. Wegscheider, G. Krausch, J. Mlynek, “Reflection scanning near-field optical microscopy with uncoated fiber tips: how good is the resolution really?” J. Appl. Phys. 81, 2499–2503 (1997).
[CrossRef]

Natan, M. J.

K. R. Brown, M. J. Natan, “Hydroxylamine seeding of colloidal Au nanoparticles in solution and on surfaces,” Langmuir 14, 726–728 (1998);K. R. Brown, D. G. Walter, M. J. Natan, “Seeding of colloidal Au nanoparticles in solution. II. Improved control of particle size and shape,” submitted to Chem. Mater.
[CrossRef]

R. G. Freeman, K. C. Grabar, A. P. Guthrie, K. J. Allison, R. M. Bright, J. A. Davis, M. B. Hommer, M. A. Jackson, P. C. Smith, D. G. Walter, M. J. Natan, “Self-assembled metal colloid monolayers—an approach to SERS substrates,” Science 267, 1629–1632 (1995);K. C. Grabar, R. G. Freeman, M. B. Hommer, M. J. Natan, “Preparation and characterization of Au colloid monolayers,” Anal. Chem. 67, 735–743 (1995);K. G. Grabar, K. J. Allison, B. E. Baker, R. M. Bright, K. R. Brown, C. D. Keating, R. G. Freeman, A. P. Fox, M. D. Musick, M. J. Natan, “Two-dimensional arrays of colloidal gold particles: a flexible approach to macroscopic metal surfaces,” Langmuir 12, 2353–2361 (1996).
[CrossRef] [PubMed]

Nieto-Vesperinas, M.

See R. Carminati, A. Madrazo, M. Nieto-Vesperinas, J.-J. Greffet, “Optical content and resolution of near-field optical images: influence of the operating mode,” J. Appl. Phys. 82, 501–509 (1997);S. I. Bozhevolnyi, “Topographical artifacts and optical resolution in near-field optical microscopy,” J. Opt. Soc. Am. B 14, 2254–2259 (1997);C. Girard, D. Courjon, “The role of scanning mode in near-field optical microscopy,” Surf. Sci. 382, 9–18 (1997), and references therein.
[CrossRef]

Novotny, L.

B. Hecht, H. Bielefeldt, Y. Inouye, D. W. Pohl, L. Novotny, “Facts and artifacts in near-field optical microscopy,” J. Appl. Phys. 81, 2492–2498 (1997).
[CrossRef]

Obermüller, C.

C. Obermüller, K. Karrai, “Far field characterization of diffracting circular apertures,” Appl. Phys. Lett. 67, 3408–3410 (1995).
[CrossRef]

Pohl, D. W.

B. Hecht, H. Bielefeldt, Y. Inouye, D. W. Pohl, L. Novotny, “Facts and artifacts in near-field optical microscopy,” J. Appl. Phys. 81, 2492–2498 (1997).
[CrossRef]

Richter, L. J.

S. J. Stranick, L. J. Richter, R. R. Cavanagh, “High efficiency, dual collection mode near-field scanning optical microscope,” J. Vac. Sci. Technol. B 16, 1948–1952 (1998).
[CrossRef]

Information about the model is available from A. Liu, G. W. Bryant, L. J. Richter, S. J. Stranick, National Institute of Standards and Technology, Gaithersburg, Maryland 20899.

C. E. Jordan, S. J. Stranick, L. J. Richter, R. R. Cavanagh, “Removing optical artifacts in near-field scanning optical microscopy by using a three dimensional scanning mode,” J. Appl. Phys (to be published).

Sandoghdar, V.

V. Sandoghdar, S. Wegscheider, G. Krausch, J. Mlynek, “Reflection scanning near-field optical microscopy with uncoated fiber tips: how good is the resolution really?” J. Appl. Phys. 81, 2499–2503 (1997).
[CrossRef]

Singham, S. B.

Smith, P. C.

R. G. Freeman, K. C. Grabar, A. P. Guthrie, K. J. Allison, R. M. Bright, J. A. Davis, M. B. Hommer, M. A. Jackson, P. C. Smith, D. G. Walter, M. J. Natan, “Self-assembled metal colloid monolayers—an approach to SERS substrates,” Science 267, 1629–1632 (1995);K. C. Grabar, R. G. Freeman, M. B. Hommer, M. J. Natan, “Preparation and characterization of Au colloid monolayers,” Anal. Chem. 67, 735–743 (1995);K. G. Grabar, K. J. Allison, B. E. Baker, R. M. Bright, K. R. Brown, C. D. Keating, R. G. Freeman, A. P. Fox, M. D. Musick, M. J. Natan, “Two-dimensional arrays of colloidal gold particles: a flexible approach to macroscopic metal surfaces,” Langmuir 12, 2353–2361 (1996).
[CrossRef] [PubMed]

Stranick, S. J.

S. J. Stranick, L. J. Richter, R. R. Cavanagh, “High efficiency, dual collection mode near-field scanning optical microscope,” J. Vac. Sci. Technol. B 16, 1948–1952 (1998).
[CrossRef]

Information about the model is available from A. Liu, G. W. Bryant, L. J. Richter, S. J. Stranick, National Institute of Standards and Technology, Gaithersburg, Maryland 20899.

C. E. Jordan, S. J. Stranick, L. J. Richter, R. R. Cavanagh, “Removing optical artifacts in near-field scanning optical microscopy by using a three dimensional scanning mode,” J. Appl. Phys (to be published).

Trautman, J. K.

E. Betzig, J. K. Trautman, “Near-field optics—microscopy, spectroscopy, and surface modification beyond the diffraction limit,” Science 257, 189–195 (1992);G. A. Valaskovic, M. Holton, G. H. Morrison, “Parameter control, characterization, and optimization in the fabrication of optical-fiber near-field probes,” Appl. Opt. 34, 1215–1228 (1995).
[CrossRef] [PubMed]

Walter, D. G.

R. G. Freeman, K. C. Grabar, A. P. Guthrie, K. J. Allison, R. M. Bright, J. A. Davis, M. B. Hommer, M. A. Jackson, P. C. Smith, D. G. Walter, M. J. Natan, “Self-assembled metal colloid monolayers—an approach to SERS substrates,” Science 267, 1629–1632 (1995);K. C. Grabar, R. G. Freeman, M. B. Hommer, M. J. Natan, “Preparation and characterization of Au colloid monolayers,” Anal. Chem. 67, 735–743 (1995);K. G. Grabar, K. J. Allison, B. E. Baker, R. M. Bright, K. R. Brown, C. D. Keating, R. G. Freeman, A. P. Fox, M. D. Musick, M. J. Natan, “Two-dimensional arrays of colloidal gold particles: a flexible approach to macroscopic metal surfaces,” Langmuir 12, 2353–2361 (1996).
[CrossRef] [PubMed]

Wegscheider, S.

V. Sandoghdar, S. Wegscheider, G. Krausch, J. Mlynek, “Reflection scanning near-field optical microscopy with uncoated fiber tips: how good is the resolution really?” J. Appl. Phys. 81, 2499–2503 (1997).
[CrossRef]

Appl. Phys. Lett. (1)

C. Obermüller, K. Karrai, “Far field characterization of diffracting circular apertures,” Appl. Phys. Lett. 67, 3408–3410 (1995).
[CrossRef]

J. Appl. Phys. (3)

B. Hecht, H. Bielefeldt, Y. Inouye, D. W. Pohl, L. Novotny, “Facts and artifacts in near-field optical microscopy,” J. Appl. Phys. 81, 2492–2498 (1997).
[CrossRef]

See R. Carminati, A. Madrazo, M. Nieto-Vesperinas, J.-J. Greffet, “Optical content and resolution of near-field optical images: influence of the operating mode,” J. Appl. Phys. 82, 501–509 (1997);S. I. Bozhevolnyi, “Topographical artifacts and optical resolution in near-field optical microscopy,” J. Opt. Soc. Am. B 14, 2254–2259 (1997);C. Girard, D. Courjon, “The role of scanning mode in near-field optical microscopy,” Surf. Sci. 382, 9–18 (1997), and references therein.
[CrossRef]

V. Sandoghdar, S. Wegscheider, G. Krausch, J. Mlynek, “Reflection scanning near-field optical microscopy with uncoated fiber tips: how good is the resolution really?” J. Appl. Phys. 81, 2499–2503 (1997).
[CrossRef]

J. Opt. Soc. Am. A (2)

J. Vac. Sci. Technol. B (1)

S. J. Stranick, L. J. Richter, R. R. Cavanagh, “High efficiency, dual collection mode near-field scanning optical microscope,” J. Vac. Sci. Technol. B 16, 1948–1952 (1998).
[CrossRef]

Langmuir (1)

K. R. Brown, M. J. Natan, “Hydroxylamine seeding of colloidal Au nanoparticles in solution and on surfaces,” Langmuir 14, 726–728 (1998);K. R. Brown, D. G. Walter, M. J. Natan, “Seeding of colloidal Au nanoparticles in solution. II. Improved control of particle size and shape,” submitted to Chem. Mater.
[CrossRef]

Phys. Rev. (1)

H. A. Bethe, “Theory of diffraction by small holes,” Phys. Rev. 66, 163–182 (1944);C. J. Bouwkamp, “On Bethe’s theory of diffraction by small holes,” Philips Res. Rep. 5, 321–332 (1950); “On the diffraction of electromagnetic waves by small circular disks and holes,” 5, 401–422 (1950).
[CrossRef]

Science (3)

E. Betzig, R. J. Chichester, “Single molecules observed by near-field scanning optical microscopy,” Science 262, 1422–1425 (1993);E. Betzig, J. K. Trautman, T. D. Harris, J. S. Weiner, R. L. Kostelak, “Breaking the diffraction barrier—optical microscopy on a nanometric scale,” Science 251, 1468–1470 (1991).
[CrossRef] [PubMed]

R. G. Freeman, K. C. Grabar, A. P. Guthrie, K. J. Allison, R. M. Bright, J. A. Davis, M. B. Hommer, M. A. Jackson, P. C. Smith, D. G. Walter, M. J. Natan, “Self-assembled metal colloid monolayers—an approach to SERS substrates,” Science 267, 1629–1632 (1995);K. C. Grabar, R. G. Freeman, M. B. Hommer, M. J. Natan, “Preparation and characterization of Au colloid monolayers,” Anal. Chem. 67, 735–743 (1995);K. G. Grabar, K. J. Allison, B. E. Baker, R. M. Bright, K. R. Brown, C. D. Keating, R. G. Freeman, A. P. Fox, M. D. Musick, M. J. Natan, “Two-dimensional arrays of colloidal gold particles: a flexible approach to macroscopic metal surfaces,” Langmuir 12, 2353–2361 (1996).
[CrossRef] [PubMed]

E. Betzig, J. K. Trautman, “Near-field optics—microscopy, spectroscopy, and surface modification beyond the diffraction limit,” Science 257, 189–195 (1992);G. A. Valaskovic, M. Holton, G. H. Morrison, “Parameter control, characterization, and optimization in the fabrication of optical-fiber near-field probes,” Appl. Opt. 34, 1215–1228 (1995).
[CrossRef] [PubMed]

Other (10)

Although unlikely, it is possible that the metal coating and the glass face lie exactly in the same plane, resulting in no topographic contrast for the aperture.

Small sample features will provide the highest-fidelity images of the probe.

No attempt was made to deconvolve the sample asperity responsible for the topographic contrast. Thus the tabulated base width is an upper limit on the true width of the probe, and the tabulated aperture ID is a lower limit on the true aperture ID.

Information about the model is available from A. Liu, G. W. Bryant, L. J. Richter, S. J. Stranick, National Institute of Standards and Technology, Gaithersburg, Maryland 20899.

We note that the three-extrema structure cannot be attributed to the weak oscillations in the calculated Y line scans for thin coatings in Fig. 9. The calculated separation between the first maxima in the Y line scans is much larger than observed (∼700 nm), and the calculated maxima appear along the wide dimension of the central minimum, not as observed along the narrow dimension.

Adjustments of ±30% of a typical dither drive amplitude ±3% off the tip resonance frequency and minimizing the shear-force damping are common optimization routes after tip exchange.

The deposition rate reported is for a rotating sample/tip. A tooling factor accounts for both the rotation and the position of microbalance relative to the sample. The reported film thicknesses are referenced through the tooling factor to the measured film thickness on slides coated in the nominal tip position.

N. van Hulst, A. Lewis, eds., Proceedings of the 4th International Conference on Near-Field Optics, Jerusalem, Israel, 9–13 February 1997; Ultramicroscopy 71 (1998).

C. E. Jordan, S. J. Stranick, L. J. Richter, R. R. Cavanagh, “Removing optical artifacts in near-field scanning optical microscopy by using a three dimensional scanning mode,” J. Appl. Phys (to be published).

Certain commercial equipment, instruments, or materials are identified in this paper to specify adequately the experimental procedure. In no case does such identification imply recommendation or endorsement by the National Institute of Standards and Technology, nor does it imply that the equipment or the materials identified are necessarily the best available for the purpose.

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Figures (10)

Fig. 1
Fig. 1

Topographic and constant-gap transmission NSOM images of 100-nm Au particles recorded with a tip having a thick metal coating. The scan area is 2.5 μm×2.5 μm. The indicated near-vertical and near-horizontal line scans are also displayed.

Fig. 2
Fig. 2

Comparison of constant-gap and reconstructed constant-height transmission NSOM images of 100-nm Au particles with the tip used in Fig. 1. The scan area is 1.4 μm×1.4 μm. The fly height for the reconstructed image is 114 nm. The indicated line scans are also displayed.

Fig. 3
Fig. 3

Constant-gap transmission NSOM images of 100-nm Au particles with the tip used in Fig. 1. In the right-hand image, the polarization orientation of the 488-nm light launched into the fiber was rotated by 90° with respect to that of the left-hand image with a λ/2 wave plate. The scan area is 1.2 μm×1.9 μm.

Fig. 4
Fig. 4

Topographic and constant-gap transmission NSOM images of 100-nm Au particles with a tip having a thin metal coating. The scan area is 2.5 μm×2.5 μm. The indicated line scans are also displayed.

Fig. 5
Fig. 5

Reconstructed constant-height transmission NSOM image of 100-nm Au particles recorded with the tip used in Fig. 4. The scan area is 2.5 μm×2.5 μm. The fly height for the reconstructed image is 61 nm. The indicated line scans are also displayed.

Fig. 6
Fig. 6

Topographic and constant-gap transmission NSOM images of 100-nm Au particles with a tip coated similarly to that used in Fig. 4. The scan area is 2.5 μm×2.5 μm. The indicated line scans are also displayed.  

Fig. 7
Fig. 7

Topographic and constant-gap transmission NSOM images of ∼115-nm Au particles recorded with a very narrow tip. The scan area is 4.5 μm×4.5 μm. The indicated near-vertical and near-horizontal line scans are also displayed.

Fig. 8
Fig. 8

Line scans of calculated NSOM images of a 100-nm×100-nm×60-nm Au particle along the X axis (parallel to the exciting electric field polarization) for different tip metal-coating thicknesses, i.e., 80, 100, 280, and 320 nm. See the text for details of the calculations.

Fig. 9
Fig. 9

Same as in Fig. 8, except that the line scans are along the Y direction (perpendicular to the exciting electric field polarization).

Fig. 10
Fig. 10

Magnitude of the X component of the calculated tip field in the XY plane 20 nm from the end of a tip with a 320-nm thick metal coating. See the text for details of the calculations.

Tables (1)

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Table 1 Summary of Results for Three Tips with Thick Metal Coatings

Equations (6)

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α(ω, rj)=30V (ω, rj)-1(ω, rj)+2,
E(ri)=E0(ri)-μ0ω2jiNG(ω, ri, rj)α(ω, rj)E(rj),
i=1, 2, , N,
Efar(r)=μ0ω2 exp(iω|r|/c0)4π|r|j=1Nα(ω, rj)exp-i ωc0 nrjME(rj),
 M=1-sin2 θ cos2 ϕ-sin2 θ sin ϕ cos ϕ-sin θ cos θ cos ϕ-sin2 θ sin ϕ cos ϕ1-sin2 θ sin2 ϕ-sin θ cos θ sin ϕ-sin θ cos θ cos ϕ-sin θ cos θ sin ϕsin2 θ.
P=12 0c002πdϕ0θcdθ|Efar(r)|2r2 sin θ,

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