SINGLE-CHARGE-EXCHANGE AND DOUBLE-CHARGE-EXCHANGE CROSS-SECTIONS FOR AR-Q-2 (Q=6, 7, 8, 9, AND 11) COLLISIONS FROM 6 EV TO 11 KEV(+H)

The cross sections for single-electron capture, including transfer ion ization, and for double-electron capture, have been measured for Ar-q + HL for q = 6, 7, 8, 9, and 11 with projectile energies from q eV to q keV. Theoretically, the cross sections for Ar6+ and Ar8+ impact wer e calculated using a molecular-orbital expansion method in the energy region from 240 eV to 80 keV, and are in good agreement with experimen t. The single-electron-capture cross sections were found to be more th an one order of magnitude larger than those for double capture in both experiment and theory. The single-electron-capture cross sections wer e also compared to the Langevin cross section, a scaling law developed by Muller and Salzborn [Phys. Lett. 62A, 391 (1977)], and the absorbi ng sphere model.