Abstract

We investigate the feasibility of overlayer attenuated-total-reflectance (O-ATR) infrared spectroscopy as a surface analytical tool for studying reactions and molecular properties of adsorbates at surfaces exposed to aqueous nonelectrolyte solutions. Through modeling an O-ATR system by assuming it to comprise three, four, or n phases of homogeneous refractive index, one can use an electric-field analysis to determine how the parameters of adsorption free energy, overlayer thickness, initial angle of incidence, and internal-reflection element refractive-index influence solvent-subtracted O-ATR infrared-absorption spectra. The theory behind such an analysis is explained, and the results of its application are presented for hypothetical O-ATR systems consisting of either a zinc selenide or a germanium internal-reflection element, an iron or hematite overlayer, an adsorbate layer, and a solution of methylene chloride in water.

© 1998 Optical Society of America

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References

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  1. G. A. Somorjai, Introduction to Surface Chemistry and Catalysis (Wiley, New York, 1994).
  2. Y. R. Shen, “Surface properties probed by second-harmonic and sum-frequency generation,” Nature (London) 337, 519–525 (1989).
    [CrossRef]
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    [CrossRef]
  4. R. Sonnenfeld, J. Schneir, P. K. Hansma, “Scanning tunneling microscopy: natural for electrochemistry,” in Modern Aspects of Electrochemistry, R. E. White, J. Bockris, B. E. Conway, eds. (Plenum, New York, 1990), Vol. 21, pp. 1–28.
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    [CrossRef]
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1995 (1)

1994 (1)

S. J. Hug, B. Sulzberger, “In situ Fourier transform infrared spectroscopic evidence for the formation of several different surface complexes of oxalate on TiO2 in the aqueous phase,” Langmuir 10, 3587–3597 (1994).
[CrossRef]

1990 (1)

1989 (1)

Y. R. Shen, “Surface properties probed by second-harmonic and sum-frequency generation,” Nature (London) 337, 519–525 (1989).
[CrossRef]

1988 (1)

1985 (1)

D. K. Ottesen, “An experimental and theoretical study of the infrared reflectance of thin oxide films on metals,” J. Electrochem. Soc. 132, 2250–2257 (1985).
[CrossRef]

1973 (1)

1951 (1)

S. G. Daniel, “The adsorption on metal surfaces of long chain polar compounds from hydrocarbon solutions,” Trans. Faraday Soc. 47, 1345–1359 (1951).
[CrossRef]

Alexander, R. W.

Apelblat, Y.

Bell, R. J.

Bertie, J. E.

Coleman, R. V.

P. K. Hansma, R. Sonnenfeld, J. Schneir, O. Marti, S. A. C. Gould, C. B. Prater, A. L. Weisenhorn, B. Drake, H. Hansma, G. Slough, W. W. McNairy, R. V. Coleman, “Scanning probe microscopy of liquid–solid interfaces,” in Scanning Tunneling Microscopy and Related Methods, R. J. Behm, N. Garcia, H. Rohrer, eds. (Kluwer, London, 1990), Vol. 184, pp. 299–313.
[CrossRef]

Daniel, S. G.

S. G. Daniel, “The adsorption on metal surfaces of long chain polar compounds from hydrocarbon solutions,” Trans. Faraday Soc. 47, 1345–1359 (1951).
[CrossRef]

Drake, B.

P. K. Hansma, R. Sonnenfeld, J. Schneir, O. Marti, S. A. C. Gould, C. B. Prater, A. L. Weisenhorn, B. Drake, H. Hansma, G. Slough, W. W. McNairy, R. V. Coleman, “Scanning probe microscopy of liquid–solid interfaces,” in Scanning Tunneling Microscopy and Related Methods, R. J. Behm, N. Garcia, H. Rohrer, eds. (Kluwer, London, 1990), Vol. 184, pp. 299–313.
[CrossRef]

Gould, S. A. C.

P. K. Hansma, R. Sonnenfeld, J. Schneir, O. Marti, S. A. C. Gould, C. B. Prater, A. L. Weisenhorn, B. Drake, H. Hansma, G. Slough, W. W. McNairy, R. V. Coleman, “Scanning probe microscopy of liquid–solid interfaces,” in Scanning Tunneling Microscopy and Related Methods, R. J. Behm, N. Garcia, H. Rohrer, eds. (Kluwer, London, 1990), Vol. 184, pp. 299–313.
[CrossRef]

Hale, G. M.

Hansen, W. N.

W. N. Hansen, “Internal reflection spectroscopy in electrochemistry,” in Optical Techniques in Electrochemistry, R. H. Muller, ed. (Wiley, New York, 1973), Vol. 9, pp. 1–60.

Hansma, H.

P. K. Hansma, R. Sonnenfeld, J. Schneir, O. Marti, S. A. C. Gould, C. B. Prater, A. L. Weisenhorn, B. Drake, H. Hansma, G. Slough, W. W. McNairy, R. V. Coleman, “Scanning probe microscopy of liquid–solid interfaces,” in Scanning Tunneling Microscopy and Related Methods, R. J. Behm, N. Garcia, H. Rohrer, eds. (Kluwer, London, 1990), Vol. 184, pp. 299–313.
[CrossRef]

Hansma, P. K.

P. K. Hansma, R. Sonnenfeld, J. Schneir, O. Marti, S. A. C. Gould, C. B. Prater, A. L. Weisenhorn, B. Drake, H. Hansma, G. Slough, W. W. McNairy, R. V. Coleman, “Scanning probe microscopy of liquid–solid interfaces,” in Scanning Tunneling Microscopy and Related Methods, R. J. Behm, N. Garcia, H. Rohrer, eds. (Kluwer, London, 1990), Vol. 184, pp. 299–313.
[CrossRef]

R. Sonnenfeld, J. Schneir, P. K. Hansma, “Scanning tunneling microscopy: natural for electrochemistry,” in Modern Aspects of Electrochemistry, R. E. White, J. Bockris, B. E. Conway, eds. (Plenum, New York, 1990), Vol. 21, pp. 1–28.

Harrick, N. J.

N. J. Harrick, Internal Reflection Spectroscopy (Wiley, New York, 1967).

Hug, S. J.

S. J. Hug, B. Sulzberger, “In situ Fourier transform infrared spectroscopic evidence for the formation of several different surface complexes of oxalate on TiO2 in the aqueous phase,” Langmuir 10, 3587–3597 (1994).
[CrossRef]

Ishida, H.

Jones, R. N.

Klocek, P.

P. Klocek, Handbook of Infrared Optical Materials (Dekker, New York, 1991).

Lan, Z.

Marti, O.

P. K. Hansma, R. Sonnenfeld, J. Schneir, O. Marti, S. A. C. Gould, C. B. Prater, A. L. Weisenhorn, B. Drake, H. Hansma, G. Slough, W. W. McNairy, R. V. Coleman, “Scanning probe microscopy of liquid–solid interfaces,” in Scanning Tunneling Microscopy and Related Methods, R. J. Behm, N. Garcia, H. Rohrer, eds. (Kluwer, London, 1990), Vol. 184, pp. 299–313.
[CrossRef]

McNairy, W. W.

P. K. Hansma, R. Sonnenfeld, J. Schneir, O. Marti, S. A. C. Gould, C. B. Prater, A. L. Weisenhorn, B. Drake, H. Hansma, G. Slough, W. W. McNairy, R. V. Coleman, “Scanning probe microscopy of liquid–solid interfaces,” in Scanning Tunneling Microscopy and Related Methods, R. J. Behm, N. Garcia, H. Rohrer, eds. (Kluwer, London, 1990), Vol. 184, pp. 299–313.
[CrossRef]

Newquist, L. A.

Ohta, K.

Ordal, M. A.

Ottesen, D. K.

D. K. Ottesen, “An experimental and theoretical study of the infrared reflectance of thin oxide films on metals,” J. Electrochem. Soc. 132, 2250–2257 (1985).
[CrossRef]

Prater, C. B.

P. K. Hansma, R. Sonnenfeld, J. Schneir, O. Marti, S. A. C. Gould, C. B. Prater, A. L. Weisenhorn, B. Drake, H. Hansma, G. Slough, W. W. McNairy, R. V. Coleman, “Scanning probe microscopy of liquid–solid interfaces,” in Scanning Tunneling Microscopy and Related Methods, R. J. Behm, N. Garcia, H. Rohrer, eds. (Kluwer, London, 1990), Vol. 184, pp. 299–313.
[CrossRef]

Querry, M. R.

Schneir, J.

P. K. Hansma, R. Sonnenfeld, J. Schneir, O. Marti, S. A. C. Gould, C. B. Prater, A. L. Weisenhorn, B. Drake, H. Hansma, G. Slough, W. W. McNairy, R. V. Coleman, “Scanning probe microscopy of liquid–solid interfaces,” in Scanning Tunneling Microscopy and Related Methods, R. J. Behm, N. Garcia, H. Rohrer, eds. (Kluwer, London, 1990), Vol. 184, pp. 299–313.
[CrossRef]

R. Sonnenfeld, J. Schneir, P. K. Hansma, “Scanning tunneling microscopy: natural for electrochemistry,” in Modern Aspects of Electrochemistry, R. E. White, J. Bockris, B. E. Conway, eds. (Plenum, New York, 1990), Vol. 21, pp. 1–28.

Shen, Y. R.

Y. R. Shen, “Surface properties probed by second-harmonic and sum-frequency generation,” Nature (London) 337, 519–525 (1989).
[CrossRef]

Slough, G.

P. K. Hansma, R. Sonnenfeld, J. Schneir, O. Marti, S. A. C. Gould, C. B. Prater, A. L. Weisenhorn, B. Drake, H. Hansma, G. Slough, W. W. McNairy, R. V. Coleman, “Scanning probe microscopy of liquid–solid interfaces,” in Scanning Tunneling Microscopy and Related Methods, R. J. Behm, N. Garcia, H. Rohrer, eds. (Kluwer, London, 1990), Vol. 184, pp. 299–313.
[CrossRef]

Somorjai, G. A.

G. A. Somorjai, Introduction to Surface Chemistry and Catalysis (Wiley, New York, 1994).

Sonnenfeld, R.

P. K. Hansma, R. Sonnenfeld, J. Schneir, O. Marti, S. A. C. Gould, C. B. Prater, A. L. Weisenhorn, B. Drake, H. Hansma, G. Slough, W. W. McNairy, R. V. Coleman, “Scanning probe microscopy of liquid–solid interfaces,” in Scanning Tunneling Microscopy and Related Methods, R. J. Behm, N. Garcia, H. Rohrer, eds. (Kluwer, London, 1990), Vol. 184, pp. 299–313.
[CrossRef]

R. Sonnenfeld, J. Schneir, P. K. Hansma, “Scanning tunneling microscopy: natural for electrochemistry,” in Modern Aspects of Electrochemistry, R. E. White, J. Bockris, B. E. Conway, eds. (Plenum, New York, 1990), Vol. 21, pp. 1–28.

Sulzberger, B.

S. J. Hug, B. Sulzberger, “In situ Fourier transform infrared spectroscopic evidence for the formation of several different surface complexes of oxalate on TiO2 in the aqueous phase,” Langmuir 10, 3587–3597 (1994).
[CrossRef]

Weisenhorn, A. L.

P. K. Hansma, R. Sonnenfeld, J. Schneir, O. Marti, S. A. C. Gould, C. B. Prater, A. L. Weisenhorn, B. Drake, H. Hansma, G. Slough, W. W. McNairy, R. V. Coleman, “Scanning probe microscopy of liquid–solid interfaces,” in Scanning Tunneling Microscopy and Related Methods, R. J. Behm, N. Garcia, H. Rohrer, eds. (Kluwer, London, 1990), Vol. 184, pp. 299–313.
[CrossRef]

Appl. Opt. (3)

Appl. Spectrosc. (1)

J. Electrochem. Soc. (1)

D. K. Ottesen, “An experimental and theoretical study of the infrared reflectance of thin oxide films on metals,” J. Electrochem. Soc. 132, 2250–2257 (1985).
[CrossRef]

Langmuir (1)

S. J. Hug, B. Sulzberger, “In situ Fourier transform infrared spectroscopic evidence for the formation of several different surface complexes of oxalate on TiO2 in the aqueous phase,” Langmuir 10, 3587–3597 (1994).
[CrossRef]

Nature (London) (1)

Y. R. Shen, “Surface properties probed by second-harmonic and sum-frequency generation,” Nature (London) 337, 519–525 (1989).
[CrossRef]

Trans. Faraday Soc. (1)

S. G. Daniel, “The adsorption on metal surfaces of long chain polar compounds from hydrocarbon solutions,” Trans. Faraday Soc. 47, 1345–1359 (1951).
[CrossRef]

Other (7)

M. R. Querry, U.S. Army Chemical Research and Development Center, Rep. ADA158623XSP (Aberdeen Proving Ground, Md., 1985).

P. K. Hansma, R. Sonnenfeld, J. Schneir, O. Marti, S. A. C. Gould, C. B. Prater, A. L. Weisenhorn, B. Drake, H. Hansma, G. Slough, W. W. McNairy, R. V. Coleman, “Scanning probe microscopy of liquid–solid interfaces,” in Scanning Tunneling Microscopy and Related Methods, R. J. Behm, N. Garcia, H. Rohrer, eds. (Kluwer, London, 1990), Vol. 184, pp. 299–313.
[CrossRef]

R. Sonnenfeld, J. Schneir, P. K. Hansma, “Scanning tunneling microscopy: natural for electrochemistry,” in Modern Aspects of Electrochemistry, R. E. White, J. Bockris, B. E. Conway, eds. (Plenum, New York, 1990), Vol. 21, pp. 1–28.

W. N. Hansen, “Internal reflection spectroscopy in electrochemistry,” in Optical Techniques in Electrochemistry, R. H. Muller, ed. (Wiley, New York, 1973), Vol. 9, pp. 1–60.

G. A. Somorjai, Introduction to Surface Chemistry and Catalysis (Wiley, New York, 1994).

N. J. Harrick, Internal Reflection Spectroscopy (Wiley, New York, 1967).

P. Klocek, Handbook of Infrared Optical Materials (Dekker, New York, 1991).

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Figures (10)

Fig. 1
Fig. 1

Schematic showing a possible experimental setup for O-ATR spectroscopy (not to scale). A double-pass multiple-internal-reflection element is coated with a thin metal or oxide overlayer and is placed in contact with a solution containing the species of interest, which adsorbs onto the overlayer surface. The infrared radiation enters and leaves at the same end of the internal-reflection element, thus traversing its length twice. At each total internal reflection, an evanescent wave interacts with the species on the surface and in solution.

Fig. 2
Fig. 2

Schematic representing the interaction of radiation in an n-phase system.

Fig. 3
Fig. 3

Dependence of absorbance on coverage for a hypothetical O-ATR system. Calculations of absorbance were performed at 1250 cm-1 with an iron overlayer thickness of 4 nm, a free energy of adsorption of -2 kcal/mol, a varying coverage of methylene chloride, and a zinc selenide internal-reflection element.

Fig. 4
Fig. 4

Calculated O-ATR spectra after subtraction of bulk solvent contributions, showing the dependence of solution-phase and adsorbed methylene chloride absorbance on the free energy of adsorption. Spectrum a, ΔG ads. 0 = -2 kcal/mol; spectrum b, ΔG ads. 0 = -4 kcal/mol; spectrum c, ΔG ads. 0 = -8 kcal/mol. All spectra are calculated with an iron overlayer thickness of 4 nm, an angle of incidence of 45°, and a zinc selenide internal-reflection element. The solution concentration is adjusted to provide a 0.50 monolayer coverage of methylene chloride on the overlayer surface.

Fig. 5
Fig. 5

Calculated O-ATR spectra after subtraction of bulk solvent contributions, showing the dependence of solution-phase and adsorbed methylene chloride absorbance on the free energy of adsorption. Spectrum a, ΔG ads. 0 = -2 kcal/mol; spectrum b, ΔG ads. 0 = -4 kcal/mol; spectrum c, ΔG ads. 0 = -8 kcal/mol. All spectra are calculated with an iron overlayer thickness of 4 nm, an angle of incidence of 45°, and a zinc selenide internal-reflection element. The solution concentration is adjusted to provide a 0.75 monolayer coverage of methylene chloride on the overlayer surface.

Fig. 6
Fig. 6

Calculated O-ATR spectra after subtraction of bulk solvent contributions, showing the dependence of solution-phase and adsorbed methylene chloride absorbance on angle of incidence. Spectrum a, θ0 = 33.90° (≅θ c ); spectrum b, θ0 = 45°; spectrum c, θ0 = 55°; spectrum d, θ0 = 65°; spectrum e, θ0 = 75°. All spectra are calculated with an iron overlayer thickness of 4 nm, a free energy of adsorption of -2 kcal/mol, and a zinc selenide internal-reflection element. The solution concentration is adjusted to provide a 0.75 monolayer coverage of methylene chloride on the overlayer surface.

Fig. 7
Fig. 7

Angular dependence of a, the coefficient q 3 Fz 3 = 0) and b, the value of the exponential decay constant in the solution β3, each normalized to its maximum values at 1250 cm-1. Other important parameters used are an iron overlayer thickness of 4 nm, a free energy of adsorption of -2 kcal/mol, a 0.75 monolayer coverage of methylene chloride, and a zinc selenide internal-reflection element.

Fig. 8
Fig. 8

Dependence of optimum angle of incidence on the weighting factor W q 3 Fz 3 =0) for some hypothetical O-ATR systems. Calculations were performed at 1250 cm-1 with either an iron overlayer thickness of 4 nm or a hematite overlayer thickness of 10 nm, a free energy of adsorption of -2 kcal/mol, a 0.75 monolayer coverage of methylene chloride, and either a zinc selenide or a germanium internal-reflection element (I.R.E.).

Fig. 9
Fig. 9

Dependence of the weighted-percent-difference sum on the weighting factor W q 3 Fz 3 =0) for hypothetical O-ATR systems with either a zinc selenide or a germanium internal-reflection element. Whereas negative values of the weighted-percent-difference sum correspond to weighting factors for which the germanium internal-reflection element would be more favorable, positive values favor the zinc selenide internal-reflection element. Calculations were performed at 1250 cm-1 with either an iron overlayer thickness of 4 nm or a hematite overlayer thickness of 10 nm, a free energy of adsorption of -2 kcal/mol, and a 0.75 monolayer coverage of methylene chloride.

Fig. 10
Fig. 10

Solvent-subtracted O-ATR spectra of systems that differ only by the choice of internal-reflection element, calculated at a weighting factor of W q 3 Fz 3 =0) = 0.5. Spectrum a was calculated with a zinc selenide internal-reflection element (n = 2.41) and an angle of incidence of 44.63°, and spectrum b was calculated with the assumption of a germanium internal-reflection element (n = 4.01) and an angle of incidence of 31.13°. Other important parameters used are an iron overlayer thickness of 4 nm and a free energy of adsorption of -2 kcal/mol. The solution concentration is adjusted to maintain a surface coverage of 0.75 monolayer of methylene chloride.

Tables (1)

Tables Icon

Table 1 Estimated Penetration into the Bulk Solution (d) so the Number of Interactions that the Radiation Has with the Solute Is the Same as for the Adsorbates, Given a Specific Free Energy of Adsorption (ΔGads. 0) and Adsorbate Coverage with the Solute Concentration Calculated with the Langmuir Isotherm

Equations (25)

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n ˆ j = n j + ik j .
A - log   R ,
A = j = 0 n - 1   d e n ˆ j i = 1 N j   α 1 c ji ,
r jp = n ˆ j - 1   cos   θ j - n ˆ j   cos   θ j - 1 n ˆ j - 1   cos   θ j + n ˆ j   cos   θ j - 1 , t jp = 2 n ˆ j - 1   cos   θ j - 1 n ˆ j - 1   cos   θ j + n ˆ j   cos   θ j - 1 , r js = n ˆ j - 1   cos   θ j - 1 - n ˆ j   cos   θ j n ˆ j - 1   cos   θ j - 1 + n ˆ j   cos   θ j , t js = 2 n ˆ j - 1   cos   θ j - 1 n ˆ j - 1   cos   θ j - 1 + n ˆ j   cos   θ j ,
n ˆ j - 1   sin   θ j - 1 = n ˆ j   sin   θ j .
R s = c 0 s a 0 s 2     or     R p = c 0 p a 0 p 2 ,
C j + 1 C j + 2 C n - 1 = a j b j c j d j ,
C j = exp - i δ j - 1 r j   exp - i δ j - 1 r j   exp i δ j - 1 exp i δ j - 1 .
δ j = 2 π ν ¯ n ˆ j   cos   θ j h j j = 1 ,   2 , n - 2 0 j = 0
R = R s + R p 2 .
a z 1 < z < z 2 = z 1 z 2   q j F z d z ,
q j = n ˆ j α j n ˆ 0   cos   θ 0
α j = 4 π ν ¯ k j = i = 1 N j   α i c ij .
A z 1 < z < z 2 1 2.303 n ˆ 0   cos   θ 0 z 1 z 2   n ˆ j i = 1 N j   α i c ij F z d z .
d e n ˆ j 1 2.303 n ˆ 0   cos   θ 0 z 1 z 2   n ˆ j F z d z .
F z = F x z + F y z + F z z 2 ,
F x z = E x z E p + z 0 2 ,   F y z = E y z E s + z 0 2 ,   F z z = E z z E p + z 0 2 .
E x z E p + z 0 = E p + z + E p - z cos   θ j E p + z 0 , E y z E p + z 0 = E s + z + E s - z E s + z 0 , E z z E p + z 0 = E p + z - E p - z sin   θ j E p + z 0
E + z E + z 0 = E j + E + z 0 exp iK zj Δ z j , E - z E + z 0 = E j - E + z 0 exp - iK zj Δ z j ,
K zj = 2 π ν ¯ n ˆ j   cos   θ j ,
Δ z j = z - z 0 - i = 1 j - 1   h i .
E j + E 0 + = t 1 t 2 t j a j a 0 , E j - E 0 + = t 1 t 2 t j c j a 0 ,
F z = F Δ z n - 1 = 0 exp - β n - 1 Δ z n - 1 ,
β n - 1 = 4 π λ Im n ˆ n - 1   cos   θ n - 1 .
A z 1 < z < z 2 q n - 1 F Δ z n - 1 = 0 2.303 × z 1 z 2 exp - β n - 1 Δ z n - 1 d z ,

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