THE EFFECTS OF CHARGE PROMOTION ON THE MEASURED CHARGE-STATE OF LOW-ENERGY LI+ SCATTERED FROM ALKALI AL(100)/

Charge promotion of an inner-shell electron during ion bombardment of a surface can strongly affect the neutralization of scattered particle s, In this work, the neutral fractions for 2.0 keV Li-7(+) scattered f rom clean and alkali-covered Al(100) are measured with time-of-flight spectroscopy. During hard collisions, a fraction of the Li particles t hat scatter from Al atoms undergo a promotion of their 1s electrons ab ove the Fermi level, with subsequent Li 1s hole creation. Differences are observed between the neutral fractions of the scattered promoted a nd non-promoted projectiles, and these neutral fractions depend on the alkali coverage. Secondary electron spectra collected during Li bomba rdment are used to identify the decay channels of the Li 1s hole. The results indicate that the Li 1s hole decays both near the surface via an Auger process and in vacuum via auto-ionization. Therefore, the lif etime of the 1s hole is on the order of the scattering time.