Surface‐Enhanced Infrared Absorption Spectroscopy

Abstract

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

Use of Surface Enhanced Infrared Absorption Spectroscopy (SEIRA) to probe the functionality of a protein monolayer

“…The ratio between these two differential absorption coefficients is 22, corresponding to the enhancement factor.]. This value is smaller than that reported by Osawa and coworkers 5 for molecules adsorbed on the bare Au surface. Considering the fact that the spacer molecule separates cyt c from the Au surface and since the decay length of the enhancement is on the order of $8 nm, 5 the surface enhancement by a factor of 20 is still appreciable.…”

“…As an optical near-field effect, the enhancement is restricted to within a short distance from the surface (decay length of $8 nm). 5 This property essentially eliminates vibrational contributions of the bulk in the IR spectrum and selectively detects signals from the adsorbed monolayer. In this paper, we present applications of SEIRAS for functional studies of different proteins at the level of a monolayer.…”

“…7 The rough surface of such a gold film is crucial for the enhancement of the IR absorption. 5 The surface of the Au film is often modified by organic chemicals to facilitate the adsorption of the sample protein (vida infra). The adsorption kinetics of the protein on such a chemically modified Au surface can be monitored in situ by SEIRAS.…”

Kinetics and Mechanism of the Electrooxidation of Formic Acid—Spectroelectrochemical Studies in a Flow Cell

“…Under these conditions mass transport in the thin-layer gap is practically inhibited, which may result in strongly misleading conclusions on the reaction process owing to the depletion of reactants as well as accumulation and possibly readsorption of by-products. [2] These limitations can be reduced by performing infrared absorption reflection spectroscopy measurements in an attenuated total reflection configuration (ATR-FTIRS), [4,5] in which a thin metal film deposited on an optical prism serves as a working electrode and the IR beam is transmitted internally from the back side of the prism to the film and totally reflected at the prism/film interface. In this technique the working electrode is freely accessible to the electrolyte.…”

“…A thin Pt film deposited on the flat reflecting side of the Si prism serves as the working electrode. [5] The electrolyte flow through the cell can be switched between different electrolytes.…”