Effects of three-dimensional time evolution in kinetic-energy distributions for electron stimulated desorption

Abstract

Quantum mechanical theory of electron stimulated desorption (ESD) of neutral particles from physisorbed layers is used to study how the kinetic-energy distributions of the desorption products are influenced by the time evolution in all spatial directions of the wave packet describing the adsorbed particle in the electronically excited state of the system. It is demonstrated that in case of the Antoniewicz scenario of desorption (properly generalized to three dimensions) different evolutions of the wave packet in the plane of the solid surface may result in drastically different distributions of particles desorbing in the direction of the surface normal even if the evolution in the latter direction is kept identical. In some cases the distributions may exhibit a multi-peak structure without different adsorption states being present - the effect never observed in a commonly used one-dimensional model. No such effects are expected for the recently proposed wave packet squeezing model of desorption. The behavior observed in the Antoniewicz model may also be present in the ESD signals from chemisorbed layers for which the Menzel-Gomer-Redhead model of desorption applies.