Resolving vibration in H+ + H2 charge transfer collisions

We measure the vibrational distribution of H2+ ions issued from charge transfer in H+ + H2 collisions to probe the details of the electron transfer mechanism from low to high impact energies. The experiments are accompanied by theoretical calculations. This joint experimental-theoretical study allows us to elicit the adequacy and accuracy of widely used assumptions in the description of molecular collisions

Target and Velocity Dependence of Charge Exchange X-Ray Emission at Solar Wind Velocities

Laboratory measurements of X-ray emissions following charge exchange (CX) between highly charged ions and neutrals are important to assess their diagnostic utility for the nonequilibrium astrophysical plasma environments, where hot flows meet cold gases. With a high-resolution X-ray quantum microcalorimeter detector, we report the CX-induced X-ray spectra and line ratios in Ne8+ on He and Kr collisions at solar wind velocities of 392, 554, 678, and 876 km s−1 , respectively. The experimentally determined line ratios quantify the differences in CX state selectivity and the following X-ray emission between He and Kr at different collision velocities. This suggests that target and velocity dependence should be considered for accurately modeling astrophysical CX plasmas

Electron collisions with /sup 4/He/sub 2//sup +/ at the TSR

The dissociative recombination (DR) of /sup 4/ He /sub 2//sup +/ has been investigated at the heavy-ion storage ring TSR in Heidelberg. Rate coefficients were measured up to collision energies of 40 eV. Vibrational level populations were monitored using the Coulomb explosion imaging technique showing relaxation to the v = 0 level (>95%) through collisions with cold electrons within 50s. Low-energy DR rate coefficients are derived for v = 0, 1 and >or=2 which show a strong v -dependence. A low-energy super-elastic collision (SEC) rate coefficient of alpha /sup v/ =/sup 1 rarr 0//sub SEC/ ( E /sub d/ = 0) ap 1.8*10 /sup -7/ cm /sup 3/ s /sup -1/ was found.Anglai