Excited-atom production by electron bombardment of alkali halides

We present experimental results which suggest a new mechanism for the production of excited atoms by electron bombardment of alkali halides. Doppler-shift measurements show that the electronically excited atoms have a thermal velocity distribution in equilibrium with the surface temperature. Measurements of the yield of excited atoms, the distribution of population among the excited states, and the dependence on incident-electron current support a model in which the excited atoms are produced by gas-phase collisions between desorbed ground-state atoms and secondary electrons. © 1986 The American Physical Society.