Quantitative SNIFTIRS

The main advantage of this method is that the absolute value of 0 can be determined directly. Howevei supplementary information such as the surface concentration, the angle of incidence, the thin-cavity thickness, and the optical constants of the film have to be determined from independent measurements. Below, we show several examples of how to apply this method. 

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Quantitative SNIFTIRS and PM IRRAS of Organic Molecules at Electrode Surfaces... 

Quantitative SNIFTIRS was introduced in 2002 and so far has been applied to the investigation of the orientation of adsorbed molecules in three systems pyridine at Au(llO) [40], citrate at Au(lll) [53], and 2-mercaptobenzimidazole at Au(lll) [54, 55]. Pyridine adsorption at gold single-crystal surfaces has long been used as a model system to study the coordination of organic molecules to metal electrode surfaces. The thermodynamics of pyridine adsorption has been thoroughly investigated with the help of the chronocoulometric technique [56-64]. The availability of the thermodynamic data made this an ideal system to test the performance of the quantitative SNIFTIRS. 

In conclusion, quantitative SNIFTIRS is a powerful technique for studying the orientation of organic molecules at electrode surfaces. It works best when... 

The quantitative SNIFTIRS and PM IRRAS were developed three years ago. They allow one to measure the angle between the direction of the transition dipole of an IR band and the normal to the electrode surface. Since the direction of the transition dipole with respect to the coordinates of the adsorbed molecule could be determined with the help of ah initio normal coordinate calculations, these methods ultimately allow one to determine the orientation of molecules adsorbed at the electrode surface. In a short period of time, they have been successfully applied to provide information concerning the orientation of molecules in several organic films. Today, thanks to the availability of these methods, investigations of thin films at the metal/solution interface may be as detailed as they were at the metal/gas or metal/vacuum interfaces in the past... 

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