Observation of K Auger electrons and K X-rays from collisions of Ar17+ and Ar18+ with surfaces

With the recently installed CAPRICE ECR ion source at the ORNL Multicharged Ion Research Facility, we now can produce sufficient Ar17+ and Ar18+ beam intensities to perform spectroscopic studies of these ions during interactions with surfaces. K X-ray spectra have been observed for both Ar17+ and Ar18+ normally incident on the Be window of a Si detector. Auger electron spectra have been measured for 283 keV Ar17+ incident on a Au(011) single crystal at 10-20 degrees. The Auger electron energy spectra show well resolved KLL and KLM Auger peaks at 2.7 keV and 3.0 keV, respectively. These observed peak energies are about 200 eV higher than those observed by Randall subsequent to K-shell excitation of a neutral Ar target by fast ions. This shift is consistent with the significant L-shell vacancy production accompanying the K-shell excitation in this case, which is expected to be absent at these lower energies investigated in the present measurements Efforts are currently in progress to measure the corresponding Auger spectrum for Ar18+