Mechanism of absorption enhancement in infrared ATR spectra observed in the Kretschmann configuration

Suzuki, Y.; Osawa, Masatoshi; Hatta, A.; Suëtaka, Wataru

doi:10.1016/0169-4332(88)90393-5

Cited by 56 publications

(40 citation statements)

References 11 publications

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“…The enhanced absorption is proportional to the average electromagnetic (EM) field within the metal film [10,11]. T heoretical model The above mentioned findings (5-7) suggest strongly that some EM mechanism is responsible for SEIRA as for the case of SERS [1].…”

Section: Methodsmentioning

confidence: 99%

Surface Enhanced Infrared Absorption Spectroscopy

et al. 1991

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Infrared (IR) absorption of molecules is enhanced , greatly (101-103 times) when they are adsorbed on or near vacuum-evaporated Ag or Au thin films. By using this surface Enhanced i$ absorption (SEIRA) phenomenon, we could obtained IR spectra of some organic molecules of a few picogram amount in good signal-to-noise ratios. Thus, the SEIRA spectroscopy is promising as a new trace analytical technique. General properties of SEIRA found in our experiments are summarized . An electromagnetic theory of this phenomenon is proposed. Key W surface enhanced infrared spectroscopy, trace analysisOptical properties of molecules are altered dramatically when they are adsorbed on or near some rough metal surfaces. Surface enhanced Raman scattering (SERS) [1] is the most prominent example. Similar surface enhanced

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Section: Methodsmentioning

confidence: 99%

Surface Enhanced Infrared Absorption Spectroscopy

et al. 1991

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“…This method, which is sometimes referred to as electric field analysis (EFA), has helped to understand the enhancement mechanisms in grazing-angle external reflection spectra of thin films on metals [101,132,149], metal overlayer ATR (MOATR) [2,132,150], and the ATR spectra of graphite-coated organic films [151]. Suzuki et al [152] interpreted the phenomenon of spectral enhancement for ultrathin films on rough metal surfaces and islandlike metal underlayers using EFA. Sperline et al [153,154] proposed evaluation of surface excess of the adsorbed molecules at the solid-liquid interface in terms of the electric field intensities.…”

Section: •mentioning

confidence: 99%

Absorption and Reflection of Infrared Radiation by Ultrathin Films

Tolstoy¹,

Чернышова²,

Skryshevsky³

2003

Handbook of Infrared Spectroscopy of Ultrathin Films

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The primary characteristics that one identifies from infrared (IR) spectra of ultrathin films for further analysis are the resonance frequencies, oscillator strengths (extinction coefficients), and damping (bandwidths), related to different kinds of vibrational, translational, and frustrated rotational motion inside the thin-film material [1][2][3][4][5][6][7]. However, the microscopic processes inside or at the surface of a film (motion of atoms and electrons) give rise to the frequency dependence (the dispersion) not only of the extinction coefficient but also of the refractive index of the film. As a result, a real IR spectrum of an ultrathin film is, as a rule, distorted by so-called optical effects. Specifically, the spectrum strongly depends upon the conditions of the measurement, the film thickness, and the optical parameters of the surroundings and substrate impeding extraction of physically meaningful information from the spectrum. Thus after introduction of the nomenclature accepted in optical spectroscopy and a brief discussion of the physical mechanisms responsible for absorption by solids on a qualitative level, this introductory chapter will concentrate on the basic macroscopic or phenomenological theory of the optical response of an ultrathin film immobilized on a surface or at an interface.The theoretical analysis of the IR spectra of ultrathin films on various substrates and at interfaces will involve two assumptions: (1) the problem is linear and (2) the system under investigation is macroscopic; that is, one can use the macroscopic Maxwell formulas containing the local permittivity. The first assumption is valid only for weak fields. The second assumption means that the volume considered for averaging, a (the volume in which the local permittivity is formed), is lower than the parameter of inhomogeneity of the medium, d (e.g., the effective thickness of the film, the size of islands, or an effective dimension of polariton), a < d. In this case, the response of the medium to the external electromagnetic field is essentially the response of a continuum. The 1

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“…A contribution of such EM effect to SEIRA was suggested also by the linear relationship between the enhanced band intensity and the average EM field intensity within the metal film [13,14]. The intensity of the enhanced EM field decays sharply as the distance from the surface (d) increases, as represented by the following equation [33,61]:…”

Section: Electromagnetic Mechanismmentioning

confidence: 99%

“…Enhanced spectra can be observed in the transmission [9,10], attenuatedtotal-reflection (ATR) [5,6,7], external-reflection [11], and diffuse-reflection modes [12]. In ATR and external-reflection measurements, the observed band intensities depend on the polarization and angle of incidence of the infrared radiation [11,13,14]. 2.…”

Section: Introductionmentioning

confidence: 99%

Surface-Enhanced Infrared Absorption

Osawa

Topics in Applied Physics

352

283

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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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Mechanism of absorption enhancement in infrared ATR spectra observed in the Kretschmann configuration

Cited by 56 publications

References 11 publications

Surface Enhanced Infrared Absorption Spectroscopy

Surface Enhanced Infrared Absorption Spectroscopy

Absorption and Reflection of Infrared Radiation by Ultrathin Films

Surface-Enhanced Infrared Absorption

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