TRAJECTORY-DEPENDENT NEUTRALIZATION OF LOW-ENERGY LI+ SCATTERED FROM ALKALI ADSORBATES ON NI(111)

Strongly trajectory-dependent neutralization is observed for low energy Li+ scattered from Cs adsorbed on Ni(111). For near glancing-exit scattering, the ion yield as a function of Cs coverage shows a pronounced peak and this behavior can be described well by a resonant charge-exchange model using the average work function. However, the yield is much smaller for near normal-exit scattering and the neutralization is mainly determined by the local electrostatic potential. Trajectory-independent, complete neutralization is observed at high coverages.