Surface topography dependent desorption of alkali halides

Electron-stimulated desorption of the (100)KBr surface has been investigate d in vacuum with noncontact atomic force microscopy and mass spectroscopy. It has been found that both desorption components (K and Br) show oscillato ry dependence on the electron dose with the oscillation amplitude decaying gradually. These results correspond with periodically varying, as a result of a layer-by-layer desorption, surface topography. it is proposed that the surface terrace edges act as traps for excited F centers diffusing in the crystal. The oscillating density of terrace edges varies surface recombinat ion/reflection rates for the F centers and modulates the balance between su rface and bull; deexcitation of the crystal.