Although there are several spectroscopic techniques for studying solid-air interfaces (which mainly yield information on the solid surface), there are few methods available for studies of solid-liquid interfaces. When the solid is a metal film, the number of useful techniques becomes even smaller. Infrared spectroscopy combined with attenuated total reflection (ATR) techniques has been used for such studies of liquid-metal interfaces, but availability of the metals has been limited to the metals used in ATR crystals. We have demonstrated that ATR can be extended to other metals by showing that spectra could be obtained on metal-coated ATR crystals. By coating a thin film of iron onto a germanium ATR crystal, we were able to observe reactions at a liquid-metal interface. However, these ATR experiments are tedious and difficult to use for studies of the effects of variables (such as temperature and pressure) on the interface reactions. In addition, polarized ATR spectra of the adsorbed film only yield certain information about the molecular order and geometry of these films, i.e., the angle the molecule makes with the metal film. Polarized transmission infrared spectroscopy would provide much needed supplemental information on molecular orientation.
R. J. Jakobsen, C. J. Riggle, and E. J. Drauglis, "Transmission Infrared Spectroscopy of Liquid-Solid Interfaces," Appl. Spectrosc. 34, 219-222 (1980)