THE ROLE OF AUGER PROCESSES IN SLOW COLLISIONS OF LI+ IONS WITH CESIATED W(110) SURFACES

We have investigated 1000 eV Li+ collisions under grazing incidence with partially cesiated W(110) surfaces by energy analysis of the ejected electrons and the Li+ and Li- ions scattered into 45-degrees. The Li- ion fraction and the electron yield are correlated with the coverage dependence of the work function, and both show maxima near the work function minimum. The maximum total electron yield is 0.12 electrons/incident ion between 200 and 1000 eV. The Li+ intensity and the Li(2p-2s) photon yield behave quite differently showing maxima near 0.2 ML Cs coverage and a marked decrease towards larger coverages. From the energy analysis of the ejected electrons it is concluded that Auger deexcitation of excited Li states populated by resonant charge transfer between the Li+ projectile and the partially cesiated surface is an efficient process