INNER-SHELL PROCESSES AS PROBES OF MULTICHARGED ION NEUTRALIZATION AT SURFACES

We have measured energy distributions for electrons emitted during grazing collisions of multicharged ions with Au and Cu single crystals in the projectile energy range 20-90 keV. The measured electron spectra are characterized by discrete peaks resulting from Auger transitions, superimposed on a broad continuum electron distribution. Auger electron emission from both projectile and target atoms has been observed. The projectile Auger electrons result from the decay of inner-shell vacancies either carried into the collision or produced by vacancy transfer from empty outer projectile levels via pseudocrossings or rotational coupling of molecular orbitals. The latter mechanism may also lead to the creation of target inner-shell vacancies which give rise to Auger electron emission characteristic of the target. An analysis of these Auger electron features is presented which is aimed, on the one hand, at elucidating detailed production mechanisms, and, on the other, at obtaining information on the time scales describing the neutralization of multicharged ions during their interaction with metal surface