Electron capture, electron loss, and deexcitation of fastH(2S2)andH(1S2)atoms in collisions with molecular hydrogen and inert gases

Collisions of ground-state $\left(1\mathrm{}{}_{}{}^2{}_{}{}^{}S\right)$ and metastable $\left(2\mathrm{}{}_{}{}^2{}_{}{}^{}S\right)$ hydrogen atoms with rare gases and molecular hydrogen have been studied in the energy range 0.5-3.0 keV. For an acceptance angle of 55 mrad, the electron loss and the electron-capture cross sections of both $\mathrm{H}\left(1\mathrm{}{}_{}{}^2{}_{}{}^{}S\right)$ and $\mathrm{H}\left(2\mathrm{}{}_{}{}^2{}_{}{}^{}S\right)$ have been measured and compared with previous experimental values. The deexcitation cross section for $\mathrm{H}\left(2\mathrm{}{}_{}{}^2{}_{}{}^{}S\right)$ has been deduced with the help of previously measured total-quenching cross sections for $\mathrm{H}\left(2\mathrm{}{}_{}{}^2{}_{}{}^{}S\right)$. The ratio of the electron-capture cross sections for $\mathrm{H}\left(2\mathrm{}{}_{}{}^2{}_{}{}^{}S\right)$ relative to $\mathrm{H}\left(1\mathrm{}{}_{}{}^2{}_{}{}^{}S\right)$ is found to be very large for argon at low energies. The effects of large-angle scattering and of highly excited states of H are discussed.