Experimental study of single and double electron capture on slow Ne8+ - He collisions using photon spectroscopy

There is still a disagreement between theory and experiment for the competition between non-radiative and radiative decay after two-electron transfer in slow collisions between highly charged ions and neutral atoms. The authors used photon spectroscopy to measure the Ne8+ - He collision system at an impact energy of 4 keV amu-1. The experiment was performed on the ECR ion source of the University of Nevada, Reno. Photons in the 50-150 Angstrom wavelength region were recorded with a multi-grating grazing incidence spectrometer. The intense single capture signals are dominated by the 1s22p 2Po - 1s23d2D transition. A large number of signals result from the retaining of both electrons on the projectile. The authors are assigning these signals using extensive atomic structure calculations. Some signals result from the decay of 2p3l levels. The project involves the comparison of the photon spectra with electron spectra from the same system. In this way not only information is obtained about the population and decay of the doubly excited states but also about the sharing between radiative and non-radiative decay channels