Electron capture by protons and alpha particles from two-electron targets

The modified two-orthogonal state expansion method published previously is applied to calculate electron capture cross sections for two-electron systems: H + , He 2+ +Be 2+ , B 3+ , C 4+ , N 5+ and O 6+ , H + +He and He 2+ +Li(1s 2 ). The active electron is described by the independent-electron model. The calculated results agree well with the existing experimental data for H + +He and He 2+ +Li collisions in the ranges 5-130 keV and below 500 keV amu -1 respectively. The author's results for H + , He 2+ +C 4+ systems are in good agreement with the experimental values for H + , He 2+ +CH 4 collisions in the intermediate energy range. A comparison with other theoretical results is presented. Scaling laws for these cross sections are examined.