Laser IR polarization spectroscopy at surfaces

摘要

A novel form of laser polarization spectroscopy is described which allows vibrational spectra of submonolayers of some adsorbates on metal surfaces to be observed. As a demonstration of its potential, spectra for CO adsorbed on a Pt(111) single crystal were obtained using a continuously tunable pulsed IR laser. The temperature dependence of the lineshape for the CO stretch in an onhyphen;top adsorption site was measured and interpreted in terms of exchangehyphen;coupling dephasing. Since sensitivity achieved with this spectroscopy is not yet as high as that obtainable with conventional IRRAS, the issue of noise sources and sensitivity in the laser spectroscopy is examined in some detail, and possibilities for future enhancements are discussed.