We report observations of photon-stimulated desorption of excited alkali-metal atoms following valence-band excitation of alkali halide crystals by tunable ultraviolet light. Excitation functions of excited Li and K atoms desorbed from LiF and KCl surfaces were measured in the photon-energy range 10–28 eV using a synchrotron light source. Simultaneous measurements of the secondary-electron yield demonstrate that excess metal on the surface is required for this process to occur; however, the temperature, time, and dose dependence of excited-atom and secondary-electron yields are uncorrelated. Possible models for the process of desorption stimulated by valence-band transitions are briefly considered.

• Received 7 October 1991

DOI:https://doi.org/10.1103/PhysRevB.45.4566