AUTOIONIZING STATE EXCITATION IN COLLISIONS OF INERT-GAS PROJECTILES WITH AN AL SURFACE AND EFFECTS OF INITIAL-STAGES OF OXIDATION

Results of an angle resolved electron spectroscopy study of low keV He +, Ne and Ne+ collisions with an Al surface are presented. Production of projectile autoionising states is demonstrated to exist not only fo r the previously known Ne+ case but also for Ne and He+. The character istics of autoionising peak line shapes suggest differences in angular distributions of the different Ne* states. Initial stages of the oxi dation of Al are studied. Saturation coverages of oxygen are reached f or exposures greater than 100 L. An initial decrease in the work funct ion is observed amounting to 160 meV for a 30 L exposure. Exposure to oxygen results in a strong decrease of autoionising state production. State-selective attenuation is observed and reflects changes in electr on transfer rates.