CHARGE-TRANSFER IN COLLISIONS OF B2-2,P-2) AND B3+(S-1) IONS WITH HE ATOMS BELOW 200 KEV((S)

Charge transfer in B2+(S-2,P-2) + He and in B3+(S-1) + He collisions i s studied theoretically by using a semiclassical molecular representat ion with 8 and 12 molecular channels for B2+ and B3+ On He systems, re spectively, at collision energies between 200 eV and 200 keV for the f ormer and between 600 eV and 50 keV for the latter. The ab initio pote ntial curves and nonadiabatic coupling matrix elements are obtained fr om the multireference single- and double-excitation configuration-inte raction (MRD-CI) calculations for the B2+-He system and a pseudopotent ial-modified configuration-interaction method for the B3+-He system. T he present cross sections for charge transfer by the ground state B2ions are found to have a broad maximum with a magnitude as large as 2x 10(-15) cm(2) at 100 keV and those by an excited B2+(P-2) State are fo und to be larger by a factor of 6 than those by the ground state in th e same energy regime. B2+-excitation cross sections are smaller than t hose for charge transfer below 1 keV, while they increasingly dominate above this energy. The present total charge-transfer cross section fo r B3+ in collisions with He is similar to that obtained in earlier wor k by Gargaud er al. [J. Phys. B 27, 3985 (1994)] both in magnitude and energy dependence, but is found to show slightly different B2+(2S) an d B2+(2p) production ratio.