NONRADIATIVE AND RADIATIVE ELECTRON-CAPTURE IN COLLISIONS OF HE-ATOMSBELOW 1000 EV( IONS WITH C)

Nonradiative and radiative electron captures in collisions of He' ions with carbon atoms at energies below 1 keV are studied theoretically b y using a molecular-orbital expansion method to calculate the adiabati c potential-energy curves and the nonadiabatic coupling matrix element s of CHe+. The corresponding scattering equations are solved. For nonr adiative transitions, electron capture into channels separating to HeC+(2D) are found to be dominant below 10 eV. However, as the energy in creases, the channels separating to He+C+(2P) take over because of the positive asymptotic energy defect. At 100 eV, the nonradiative captur e cross section is 5 X 10(-17) cm2. The radiative electron-capture cro ss section is found to be very small, with a magnitude nowhere greater than 10(-22) cm2.