Kinetic-energy distributions of neutrals desorbed by electron impact from adsorbates on metal surfaces

The kinetic energies of neutrals desorbed by electron impact [CO from chemisorbed CO on Ru(001), and N2O and N2 from chemisorbed and physisorbed N2O 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 N2O 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.