Absolute rates for radiative and non-radiative collisional deexcitation of metastable He+ (2s) in targets of variable polarizability

A method devised to measure separate absolute rates for deexcitation of metastable hydrogenic atoms and ions via radiative (R) and non-radiative (NR, e.g. Penning ionization (PI)) processes has first been applied to 6.6 keV He+(2s) collisions in Ar. Preliminary results of this new method were presented at the 1997 Budapest ISIAC conference by Henning Schmidt; subsequently, refined results have been published in the June 1998 issue of Phys. Rev. A, Rapid Communications, p. R4082. Additional data for the same projectiles have now been acquired for He and Xe targets. Preliminary comparisons of the R and NR rates for these new targets with the now final results for Ar as well as comparisons of the corresponding branching ratios are the primary focus of this paper. (C) 1999 Elsevier Science B.V. All rights reserved.