Kinetic-Energy Distributions of Neutrals Desorbed by Electron Impact from Adsorbates on Metal Surfaces

Abstract

The kinetic energies of neutrals desorbed by electron impact [CO from chemisorbed CO on Ru(001), and ${\mathrm{N}}_2$O and ${\mathrm{N}}_2$ from chemisorbed and physisorbed ${\mathrm{N}}_2$O on Ru(001)] have been measured by a time-of-flight technique. Wide variations are found for peak energies and low-energy behavior. Theoretical calculations are presented for physisorbed ${\mathrm{N}}_2$O which exclude a desorption mechanism via electronically induced vibrational predissociation of the surface bond, and support desorption from the repulsive region of the ground state which is reached via a strongly bound ionic state.