Desorption Induced by Sub-picosecond Laser Pulses: NO/Pd (111)

Abstract

The possibility of desorption of atomic or molecular species from surfaces occurring by non-thermal means has recently attracted considerable interest.1 One of the most intriguing cases is that of desorption from the surface of a metal substrate, for which the lifetimes of excited, non-equilibrium states in both the bulk and surface region are expected to be extremely short. In this paper, we report results on the desorption of NO from chemisorbed states on a Pd (111) surface induced by exposing the surface to laser radiation of 2-eV photons in a 200 fsec pulse. Analysis of these results in conjunction with our earlier study of NO desorption from Pd (111) by nanosecond laser pulses2 indicates that by depositing energy into the surface on a sub-picosecond timescale we are able to observe a non-thermal desorption mechanism. Here we outline the nature of our experiment and present data concerning the yield and vibrational energy distribution for the desorbed NO molecules.