Angular distributions of neutral CO desorbed by electron impact from chemisorbed CO on Ru(001), and of neutral ${\mathrm{N}}_2$O and ${\mathrm{N}}_2$ from chemisorbed and physisorbed ${\mathrm{N}}_2$O on Ru(001), have been measured and compared to angular distributions of desorbing ions. All distributions are peaked around the surface normal. Angular widths of neutrals are generally broader than those of ions, but are much narrower than for thermal desorption, and show large differences. The results are discussed in terms of mechanisms of ionic and neutral desorption.

• Received 29 November 1982

DOI:https://doi.org/10.1103/PhysRevLett.50.986