INNER-SHELL PROMOTIONS IN LOW-ENERGY LI-AL COLLISIONS AT CLEAN AND ALKALI-COVERED AL(100) SURFACES()

Spectra of scattered ions and ion-induced electron emissions are used to investigate the electronic processes that occur during 0.4-5.0-keV Li+ bombardment of clean and alkali-atom-covered A1(100). The results show that Li Is electrons are promoted during hard Li-Al collisions, b ut not during Li-K or Li-Na collisions. Consequences of the inner-shel l electron promotions are evident in the inelastic loss, neutralizatio n behavior, and electron emissions of the scattered Li particles. Spec tra of scattered Li+ ions exhibit discrete-loss features, which are re sistant to the usual increase in resonant neutralization that accompan ies the deposition of alkali atoms on the surface. The loss features a re due to Li 1s excitation via electron promotion, while the productio n of ions away from the surface via autoionization is responsible for their lack of response to alkali-atom adsorption. Spectra of ion-induc ed electron emissions confirm that Li(1s2s(2)) is produced and that i t undergoes autoionization.