Design and construction of a polarization modulated infrared reflection absorption spectrometer and validation with carbon monoxide adsorption on a platinum (100) surface.

摘要

A polarization modulated infrared reflection absorption spectroscopy (PM-IRRAS) instrument was designed, constructed, and validated with CO adsorption on a Pt(100) surface. The instrument is attached to a reaction chamber which can accommodate pressures from 1*10-9 Torr up to 760 Torr, to allow the study of model catalysts under a wide range of pressures, to cross the 'pressure gap' between most surface science methods and more common catalytic conditions. The system works as designed, with a signal to noise ratio slightly lower than the previous IRRAS system. It allows for studies at the same UHV conditions as previous literature, as well as conducting studies of the same model catalyst under significantly higher pressures. The Pt(100)/CO studies agree with previous literature at low pressures, and find no significant change at higher pressures. Increased pressure leads to a higher surface concentration, determined from a blue shift in the location of the CO atop peak from 2080 cm-1 to 2090 cm-1 , but no new bands were observed.