X-Ray Emission From Bi exp 50+ to Bi exp 71+ Ions Incident on a Gold Surface

Bismuth ions with charge states q = 50-71 from the Livermore National Laboratory's EBIT were accelerated to energies of q . (7 keV) and directed to a gold target. Using a Si(Li) detector, two families of X-rays were observed, one of these in the range of 750-2000 eV and the other between 2500-6000 eV. Both families are found to shift to higher energies with increasing incident ion charge state. The lower energy group which dominates the spectra for lower incident charge states is attributed to the filling of vacancies in the N shell while the higher energy group, which predominates for the higher incident charge states, is attributed to the filling of M-shell vacancies. M X-rays are observed even for those incident charge states for which M vacancies are not expected. A similar result observed for uranium ions incident upon beryllium target was attributed by Schuch and coworkers to a dielectronic excitation mechanism.