Photochemistry of adsorbed molecules. V. Ultraviolet photodissociation of OCS on LiF(001)

Dynamical studies of the UV photochemistry of submonolayer coverages of OCS physisorbed on 116 K LiF(001) are presented. Following pulsed ultraviolet laser irradiation (λ 222 nm), translational energy and angular distributions were obtained for photolysis products by angle-resolved time-of-flight mass spectrometry. Photolysis of adsorbates gave rise to distributions which differed markedly from gas phase photodissociation. Energetic sulphur and CO fragments were detected for coverages ≥10−5 monolayers. The cross section for photolysis in the adsorbed state was enhanced 103–104× relative to the gas phase. The dynamics for these photoprocesses were found to vary with adsorbate coverage, indicative of a catalytic influence of the surface on the photochemistry.