Stark-induced X-ray emission from one and two-electron Rydberg ions: Theory and Experiment

M.A. Gearba, R.A. Komara, S.R. Lundeen
(Colorado State University),

C.J. Verzani, C.W. Fehrenbach, B.D. DePaola
(Kansas State University)

Previous studies have demonstrated that the X-ray spectrum emitted by highly excited H-like and He-like ions can be modified by the presence of quite small (\sim 10V/cm) external electric fields[1]. In particular, the direct decay to the 1s ground level is enhanced by the presence of fields strong enough to Stark-mix an entire Rydberg manifold, since in this case the rapid decay of the nP state is the dominant decay mode of all Stark states with m=-1,0, or 1. As a result, observations of this Stark-enhanced decay is one measure of the population fraction in these low m states[1]. In continuing studies of this process, the Rydberg ions are formed by charge transfer between a range of bare and H-like ions (Ne^10+, Si^13+, Si^14+, and Ar^17+) and a range of Rb Rydberg targets (n_t=8,9,10,12,14). Observations are compared with a theoretical model based on CTMC simulations of the n,l,m population distributions expected in such charge transfer collisions. While this comparison confirms the basic mechanism of the Stark-induced emission, other aspects of the observations are not in good agreement with the model.

This work was supported by the Chemical Sciences, Geosciences and Biosciences Division,
Office of Basic Energy Sciences, Office of Science, U.S. Department of Energy.

Submitted to DAMOP, May 2004 in Tucson, AZ.

 

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