Electron capture from excited hydrogen atoms by highly charged beryllium and carbon ions

The cross sections for electron capture in collisions of bare and helium-like ions of Be and C with excited H atoms (n = 2) have been calculated by a molecular-state close-coupling method in a collision energy range of 60 eV/amu-6 keV/amu. Calculated results show that these cross sections are remarkably larger than those for collisions with ground-state H atoms. For example, for collisions of Be2+, Be4+, C4+, and C6+ ions with H(2s) atoms at ∼1 keV/amu, the cross sections are 190x10-16 cm2, 610x10-16 cm2, 920x10-16 cm2, and 720x10-16 cm2, respectively. In contrast, the cross sections for collisions with ground-state H atoms are 25x10-16 cm2, 35x 10-16 cm2, 30x10-16 cm2, and 40x10-16 cm2, respectively.