UV-LASER-INDUCED DESORPTION OF NO FROM PT(111)

Ultraviolet-laser-induced desorption of NO molecules from a Pt(111) su rface is investigated at 80 K by state-selective detection. We find tw o distinctive desorption channels are operative on an as-adsorbed surf ace and a surface annealed at 220 K. Rotational energy distributions a re Boltzmann on as-adsorbed Pt(111) and non-Boltzmann on annealed Pt(1 11) with inverted population of spin-orbit states. Rotational, vibrati onal, and translational temperatures of NO from an as-adsorbed surface are increased with the incident photon energy. The effect of the adso rption state on desorption and the desorption mechanism are discussed.