LASER-INDUCED PHOTOCHEMISTRY OF NITROUS-OXIDE ON A PT(111) SURFACE

Photochemistry of N2O Molecularly adsorbed on clean and oxygen-covered Pt(111) surfaces has been studied using pulsed excimer laser light with 6.4 eV (193 nm) photon energy. From thermal desorption spectra before and after photon irradiation, it is found that adsorbed N2O molecules are dissociated with 193 nm photons to produce oxygen adatoms. In addition, NO is generated by secondary reactions of photofragments with N2O. The cross sections of total depletion and photodissociation of N2O adsorbed on O-covered Pt(111) are not much different from those on clean Pt(111). The dependence of the photodissociation yield on photon polarization and incident angle is in good agreement with that of the bulk absorption predicted from classical electrodynamics. This strongly indicates that the substrate excitation is mostly responsible for the primary step of the photochemistry of N2O on Pt(111).