Infrared Reflection Absorption Spectroscopy on Single-crystal Surfaces in the Presence of Gaseous Molecules : Cancellation of Absorption Bands of Gaseous Molecules using a Synchronized Revolving Polarizer and Application to the Study of Reversible Adsorption of Ethylene on a Pt (111) Surface

In-situ observation of the adsorbates on single-crystal metal surfaces in the presence of gaseous molecules at ca. 103 Pa has become possible by using a synchronously revolving polarizer with Fourier transform infrared reflection absorption spectroscopy (IRAS). The IRAS spectra demonstrated excellent elimination of the absorption peaks of gaseous species, and the absorption bands of the adsorbates on the surface were clearly visible. An ultra-high vacuum system equipped with a small high-pressure cell was designed for application from the ultra-high vacuum condition to atmospheric pressures. The length of the optical path in the cell was set as short as possible to restrict the absorption by gaseous molecules. The study of adsorption of ethylene in the presence of gaseous ethylene at around 103 Pa was demonstrated as an example of the application.