Charge transfer in low-energy collisions of Be³⁺ and B⁴⁺ ions with He

The nonradiative charge-transfer processes of Be³⁺(1s)/B⁴⁺(1s) colliding with He(1s²) are investigated by the quantum-mechanical molecular orbital close-coupling (QMOCC) method from 10 eV/u to 1800 eV/u. Total and state-selective cross sections are obtained and compared with other results available. Although the incident ions have the same number of electrons and collide with the same target, their cross sections are different due to the differences in molecular structure. For Be³⁺(1s) + He(1s²), only single-electron-capture (SEC) states are important and the total cross sections have a broad maximum around E = 150 eV/u. While for B⁴⁺(1s) + He(1s²), both the SEC and double-electron-capture (DEC) processes are important, and the total SEC and DEC cross sections decrease rapidly with the energy decreasing. (paper)