Silver island films for surface-enhanced infrared absorption spectroscopy: effect of island morphology on the absorption enhancement

Nishikawa, Yuji; Nagasawa, Tadahiro; Fujiwara, Kunihiro; Osawa, Masatoshi

doi:10.1016/0924-2031(93)87021-k

Cited by 99 publications

(102 citation statements)

References 26 publications

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“…The surface of the thin gold film may be rough and consist of many separated islands. 11 The positive shift of the wavenumbers and the greater values of Γ in Table 1 support the presence of the orientational distribution of the methyl groups. We estimated the degree of the orientational distribution in the TIR condition by assuming a simple Gaussian form:…”

Section: Orientation Analysis Of the Hdt Molecules On The Thin Gold Filmmentioning

confidence: 77%

“…The evaporation conditions affected the morphology of thin metal films and were critical for enhancing the electric field at adsorbate/metal interfaces, as suggested by Nishikawa et al using BaF2 and Ge prisms. 11 In the deposition, we followed their conditions so that separated metal islands can be formed on the substrate surface. For the external reflection (ER) condition, 200 nm thickness gold deposited on mica was prepared as described elsewhere.…”

Section: Substratementioning

confidence: 99%

“…For the study of surface phenomena at various interfaces, the total internal reflection (TIR) condition has been used in a number of spectroscopic measurements, 1 such as fluorometry, [2][3][4][5][6][7][8][9] surface enhanced infrared spectroscopy (SEIRA), [10][11][12] second harmonic generation, [13][14][15][16][17][18][19][20][21] and sum frequency generation (SFG). [22][23][24][25] There are two advantages when one uses the TIR condition.…”

Section: Introductionmentioning

confidence: 99%

“…It has been successfully employed to detect adsorbed species on metal in the SEIRA, where the thickness of the metal film is about 10 nm on a transparent substrate. [10][11][12] Recently, Williams et al showed that the TIR arrangement can also be employed to detect SFG signals from alkanethiols adsorbed on a thin gold film. 24 However, detailed analysis of the sum frequency vibrational spectra has not been reported.…”

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confidence: 99%

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Total-internal-reflection Broad-bandwidth Sum Frequency Generation Spectroscopy of Hexadecanethiol Adsorbed on Thin Gold Film Deposited on CaF, 2

et al. 2003

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IntroductionFor the study of surface phenomena at various interfaces, the total internal reflection (TIR) condition has been used in a number of spectroscopic measurements, 1 such as fluorometry, 2-9 surface enhanced infrared spectroscopy (SEIRA), [10][11][12] second harmonic generation, [13][14][15][16][17][18][19][20][21] and sum frequency generation (SFG). [22][23][24][25] There are two advantages when one uses the TIR condition. First, both incident light to the interface and reflected light or generated light from the interface travel in only one of the two phases adjacent to the interface, which circumvents bulk absorption by the other phase. One corollary is the freedom of changing the composition of the adjacent phase that has a lower refractive index. Second, high sensitivity to the interfaces can be achieved owing to the enhancement of the electric field at the interfaces. 1 The TIR arrangement can be employed at metal interfaces if a very thin metal film is used to avoid the absorption of light. It has been successfully employed to detect adsorbed species on metal in the SEIRA, where the thickness of the metal film is about 10 nm on a transparent substrate. [10][11][12] Recently, Williams et al. showed that the TIR arrangement can also be employed to detect SFG signals from alkanethiols adsorbed on a thin gold film. 24 However, detailed analysis of the sum frequency vibrational spectra has not been reported. SFG in the TIR arrangement has some potential as a powerful tool to study molecular orientations at metal/liquid interfaces, such as electrochemical interfaces, because it is free from bulk absorption and has interfacial sensitivity in the order of nanometers. Unlike surface plasmon resonance and capacitance measurements that have been used as sensitive means of detecting adsorption and molecular interaction at the interfaces, TIR-SFG will enable us to obtain molecular information on the solution side of the interfaces. One drawback of the TIR arrangement is the roughness of the metal surfaces. The roughness is prerequisite for high sensitivity and can complicate the interpretation of the experimental data because of the orientational distribution of molecules in comparison with those adsorbed on a single crystal surface. It is therefore of crucial importance to assess the degree of the variation in orientation of molecules.By using broad-bandwidth sum frequency generation (BBSFG) [26][27][28] we recently analyzed the orientation of alkanethiols adsorbed on Au(111). 29It is worthwhile to examine the applicability of BBSFG in the TIR condition at metal interfaces to obtain SFG spectra with higher resolution. In the present paper, we report the results of TIR-BBSFG measurements for hexadecanethiol (HDT) adsorbed on a thin gold film on CaF2. We will show that BBSFG can be successfully employed in the orientation analysis of the HDT molecules and that the methyl groups of HDT are much more randomly orientated than those on Au(111) on mica. Experimental SubstrateA hemicylindrical CaF2 prism (Pier Optic...

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Section: Orientation Analysis Of the Hdt Molecules On The Thin Gold Filmmentioning

confidence: 77%

Section: Substratementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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Total-internal-reflection Broad-bandwidth Sum Frequency Generation Spectroscopy of Hexadecanethiol Adsorbed on Thin Gold Film Deposited on CaF, 2

et al. 2003

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“…2. The enhancement depends greatly on the morphology of the metal surface [15]. Vacuum-evaporated [5,6,7] and electrochemically deposited [16,17,18,19] metal island films, and metal colloids [20,21] are good enhancers.…”

Section: Introductionmentioning

confidence: 99%

Surface-Enhanced Infrared Absorption

Osawa

Topics in Applied Physics

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Abstract. Molecules adsorbed on metal island films or particles exhibit 10-1000 times more intense infrared absorption than would be expected from conventional measurements without the metal. This effect is referred to as surface-enhanced infrared absorption (SEIRA) to emphasize the similarities with surface-enhanced Raman scattering (SERS). The electromagnetic interactions of the incident photon field with the metal and molecules play predominant roles in this effect. The chemical interactions of the molecules with the surface can give additional enhancement. The enhancement mechanisms and some applications of SEIRA.

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Surface‐Enhanced Infrared Absorption Spectroscopy

Osawa¹

2001

Handbook of Vibrational Spectroscopy

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The sections in this article are Introduction Nature of Surface‐Enhanced Infrared Absorption Enhancement Mechanisms Electromagnetic Mechanism Chemical Mechanisms Experimental Procedures Sample Preparation Preparation of Surface‐Enhanced Infrared Absorption‐Active Metal Surfaces Spectral Acquisition Determination of Molecular Orientation Applications Analysis of Trace Chemicals Biological Applications Characterization of Thin Organic Films and Solid Surfaces In situ Study of Electrochemical Dynamics Conclusion

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Silver island films for surface-enhanced infrared absorption spectroscopy: effect of island morphology on the absorption enhancement

Cited by 99 publications

References 26 publications

Total-internal-reflection Broad-bandwidth Sum Frequency Generation Spectroscopy of Hexadecanethiol Adsorbed on Thin Gold Film Deposited on CaF, 2

Total-internal-reflection Broad-bandwidth Sum Frequency Generation Spectroscopy of Hexadecanethiol Adsorbed on Thin Gold Film Deposited on CaF, 2

Surface-Enhanced Infrared Absorption

Surface‐Enhanced Infrared Absorption Spectroscopy

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