Perturbative treatments of photo-stimulated desorption and dissociation on metal surfaces induced by single and multiple electronic transitions

Photo-stimulated desorption and dissociation of small molecules adsorbed on metals are investigated in both the DIET and DIMET limits. A theoretical model is developed based on a perturbative treatment of substrate-mediated transitions. In this model, the system evolves according to the time-dependent Schrodinger equation except for transitions between the neutral and ionic states, which are induced by a series of delta pulses delayed by a pre-specified time (tau). Two examples are studied: the photo-stimulated substrate-mediated desorption of nitric oxide and the dissociative electron attachment of methyl bromide. Translational energy distributions and product yields in both the DIET and DIMET limits are calculated and compared. The influence of the time delay between the excitation and deexcitation is explored.