Coupled subshell description of the L-shell ionization in asymmetric ion-atom collisions

Investigation of the vacancy sharing process in L-shell ionization of gold and bismuth by boron ions

“…These refined quantum mechanical calculations could reproduce the main tendencies of the L-subshell cross section data (including L 3 -subshell alignment parameters) in a broad range of the collision energy and target and projectile atomic number. Theoretical investigations by other authors (Finck et al 1983, Jitschin et al 1983b, Kocbach 1984, Spies et al 1984, Becker 1985, Berinde et al 1985, Amundsen and Jakubassa-Amundsen 1988, Legrand et al 1989,1991, Trautmann and Baur 1989) also supported the picture of the vacancy sharing process in the heavy-ion induced L-shell ionization.…”

“…In our opinion the applied factors are not very large, and can be explained by several insufficiencies of both models. As a probable reason we may mention the overestimation of the binding effect when it is calculated with use of hydrogenic wavefunctions (Vigilante et al 1990, Legrand et al 1991. As shown in figures 1(a) and 2(a), the ECPSSR theory is incapable of completely describing the experimental data.…”

“…We note that for a more consequent normalization we scaled the diagonal coupling matrix elements by a suitable factor to ensure that the increased binding energies were equal to the united-atom binding energies at zero internuclear separation. This correction is necessary because the binding effect is overestimated when hydrogenic wavefunctions are used (Vigilante et al 1990, Legrand et al 1991.…”

“…The couplings between the L substates were described by transition probabilities instead of transition amplitudes, which means that possible interference effects were neglected. Later more refined approaches based on the second-order Born approximation and the coupled-channel formalism have been worked out 0953-4075/96/112253+12$19.50 c 1996 IOP Publishing Ltd and applied to the description of the L-shell ionization in large number of collision systems (Sarkadi and Mukoyama 1984, 1987, 1990, 1991, Sarkadi and Papp 1985, Sarkadi 1986a, b, 1989. These refined quantum mechanical calculations could reproduce the main tendencies of the L-subshell cross section data (including L 3 -subshell alignment parameters) in a broad range of the collision energy and target and projectile atomic number.…”

Coupled channel treatment of the L-shell ionization in ion-atom collisions

“…To summarize, the CSA with the simple inclusion of the screening effect presented in this work yields a major improvement of the description of the L-subshell ionization probabilities relative to SCA. As a consequence, the integral cross sections (Berinde et al 1988a) are also much better reproduced by the present approach (Legrand et al 1990). However, some discrepancies between the theory and experiment, such as the underestimation of the &,(b j at smaii impact parameters, stiii remain unexpiained within this model of direct vacancy production and sharing.…”