Double electron capture in collisions of the helium-like ions N5+, O6+and Ne8+with helium atoms
- 28 March 1989
- journal article
- Published by IOP Publishing in Journal of Physics B: Atomic, Molecular and Optical Physics
- Vol. 22 (6) , L121-L127
- https://doi.org/10.1088/0953-4075/22/6/004
Abstract
A fitting procedure of 1s23l3l' lines observed in A(z-2)+(1s2)+He collisions (Z=7, 8 and 10), at 10 q keV collision energy (q=Z-2) and 10' observation angle, allows the authors to compare new theoretical positions and lifetimes, calculated with a Feshbach approach, and experimental electron spectra. It is found that the spin conservation rule holds and that only singlet states are populated in these capture processes. As in N7+ and O8++He systems, but to a lesser extent, capture into the highest angular momentum 1G state is favoured in O6+ and Ne8++He systems and accounts for 26% of the double capture at 10'. In N5++He, the L distribution is broader and no L value is clearly predominant. Discrepancies between theoretical line shapes, determined from an incoherent sum of the intensities, and experiment are observed near the 3s3p 1P and 3s3d 1D positions in N5+ and O6++He spectra. A coherent fit shows that they are due to interferences between the transition amplitudes of these two states; ML=0 and 1 sublevels are found to be excited.Keywords
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