ELECTRON-EMISSION IN SLOW COLLISIONS OF K+ IONS WITH ALKYLATED (K, CS) W (110) SURFACES

We have investigated K+ collisions (200 to 1000 eV) under grazing incidence with partially alkalated (K, Cs) W (110) surfaces by energy analysis of the ejected electrons. Three different mechanisms for electron emission could be identified (1) Kinetic emission mainly confined to projectile energies greater than 300 eV, (2) Auger deexcitation of excited projectile valence states yielding electrons with energies up to about 2.9 eV and (3) Creation of inner shell vacancies (Cs(5p-1) and K(3p-1)) which gives rise to Auger type processes (OVV and MVV) and to the formation of autoionizing states of the type A (np5n's n''l) (A = Alkali atom). The relative importance of the three mechanisms is studied as a function of the alkali coverage of the surface and of the projectile's energy.