Europhys. Lett.
Volume 74, Number 6, June 2006
Page(s) 992 - 998
Section Atomic and molecular physics
Published online 17 May 2006
Europhys. Lett., 74 (6), pp. 992-998 (2006)
DOI: 10.1209/epl/i2006-10056-2

Identification of distinct two-electron transfer processes in $\chem{O^{6+}+Na}$ collisions

S. Knoop, V. G. Hasan, R. Morgenstern and R. Hoekstra

KVI, Atomic Physics, Rijksuniversiteit Groningen - Zernikelaan 25 NL-9747 AA Groningen, The Netherlands

received 10 March 2006; accepted in final form 24 April 2006
published online 17 May 2006

Two-electron capture in 7.5 $\un{keV\,amu^{-1}}$ $\chem{O^{6+}+Na}$ collisions is investigated by measuring the momenta of the $\chem{Na^{2+}}$ recoil ions. The Q-value spectrum shows two groups of two-electron capture channels, namely 3l3l' and 3lnl' ($n\geq6$). The manifolds in between, 3l4l' and 3l5l', are barely populated. The population of the 3lnl' ($n\geq6$) states occurs via two consecutive one-electron transitions, while transfer to the 3l3l' channels occurs at a direct crossing with the entrance channel. These findings show that for capturing two non-equivalent electrons the population of symmetric and asymmetric nln'l' projectile states can also be described by dielectronic and monoelectronic transitions, respectively, just as for the capture of two equivalent electrons from noble gasses. However, the population mechanisms are the other way round.

34.70.+e - Charge transfer.
32.80.Pj - Optical cooling of atoms; trapping.

© EDP Sciences 2006