Role ofF-Center Diffusion in the Electron-Stimulated Desorption of Metal Atoms from Alkali Halides

Measurements of the time history of ground-state neutral-lithium desorption from LiF during pulsed electron irradiation have resulted in a new model for the lithium desorption mechanism. We show that the slow diffusion to the surface of bulk $F$ centers created by the electron beam is the rate-controlling factor responsible for most of the time history of the lithium desorption rather than the thermal evaporation of the metal from the surface. Comparison between theoretical and experimental time dependences yields values for the $F$-center diffusion constant and its activation energy for diffusion.