Surface Studies by Infrared Laser Photoacoustic Spectroscopy

Abstract

Vibrational spectroscopies have been a valuable tool for the investigation of the structure and the dynamics of molecules. Whereas earlier experiments had concentrated on studies of molecules in the gas phase, the last ten years have seen a rapid development of vibrational spectroscopies applied to molecules on surfaces [1]. This makes available important information about gas-surface interactions: if a molecule sticks to a solid material the vibrational frequencies usually change compared to their undisturbed values in the gas phase or solid state. The measurement of these shifts can yield information on the bonding of the molecules to the surface. In addition, the vibrations of different molecules on the substrate can mutually influence each other as the result of dipole-dipole coupling. This can give rise to coverage dependent shifts of vibrational bands and be used to investigate lateral interactions.