Electron stimulated desorption of excited neutrals from the surface of solid rare gas

Electron stimulated desorption from the surface of rare-gas solids (Ar, Kr, and Xe) was studied. Electronic excitations in a solid, which are produced by electron irradiation, induce the desorption of multiply charged ions, neutral molecules, and excited neutrals from the surface. The kinetic energies of the excited neutrals were determined by time-of-flight measurement: 0.6 and 0.04 eV for Ar, 0.7 eV for Kr, and 1.5–2 eV for Xe at the peak of energy distribution. These metastables, except Xe, are thought to be originated by a decay process of an ionic dimer to an excimer (R+R++e−→R+R*) before self-trapping of exciton. The authors found that H2 physisorbed on the surface of the solid Xe, enhancing the desorption of the excited neutral.