M Barat

Single and double electron capture by C4+ ions colliding with helium target

Differential cross sections for single and double electron capture by C4+ ions on helium target are measured at energies of 6 and 9.6 keV. These data are interpreted using a simple four-state model. Concerning the double capture, the theoretical analysis shows that a simultaneous two electron transition induced by electron-exchange interaction provides a possible alternative to transitions purely induced by electron-electron interaction usually considered.

Differential cross sections and electron transfer mechanisms in multiply charged ion-atom collisions

Differential cross sections for single- and double-electron capture in collisions of fully stripped, H-like and He-like projectiles on H2 and rare gas targets are reported. Theoretical analysis is derived in the framework of the impact parameter approximation. The importance, for simultaneous two-electron transfer, of second-order one-electron interaction terms, is emphasised.

Transfer ionisation and two-electron capture processes in N6+-He collisions at 3-34 keV energies

Energy-gain spectroscopy is used to investigate the various electron capture channels in N6+-He collisions. It is found that, in addition to the dominant one-electron capture into the N5+ (n=3) states, the two-electron processes and especially transfer ionisation make a large contribution to the production of N5+ ions for the highest energies investigated.

Transfer excitation in F6+ and Ne7+ ions colliding with He and Ne targets

An experimental study is presented, using coincident energy gain spectroscopy, of transfer excitation processes in the low keV energy range, for lithium-like F6+ and Ne7+ ions colliding with He and Ne atoms. A theoretical model is developed in a quasimolecular framework, implying the same basic interactions as invoked in non-resonant transfer excitation (NTE), a mechanism well established at large collision velocity. This model describes transfer excitation as a two-step process essentially governed by the electron-nucleus interactions.

Collisions of metastable He-like C4+ ions on He and H2 targets

Single and double electron transfer collisions into metastable C4+(1s2s)3S have been studied. With He as a target, both single and double electron capture take place dominantly in the n=2 shell and the decay from there on is mostly through autoionization, whereas with H2 single electron capture populates C3+(1s2s3l) states which stabilize both by autoionization and radiation. The discussion is focused on the influence of the 2s metastable electron on the capture mechanism.

Coincident energy gain spectroscopy of electron capture in multiply charged ions colliding with He, H2 and heavy rare-gas targets

Coincident energy gain spectroscopy is applied to the study of single- and double-electron capture by multiply charged ions on different targets. Attention has been focused on the determination of branching ratios between the two processes. The influence of collision energy and the charge state of the projectile on the relative state population is discussed.