Scattering with Charge Exchange to the StateH(2p)for the SystemsH++ He andH++ Ar

Abstract

Studies have been made of differential scattering with charge exchange to the $2p$ state of hydrogen for the systems ${\mathrm{H}}^{+}$ + Ar and ${\mathrm{H}}^{+}$ + He. Fast hydrogen atoms in the state $\mathrm{H}(2p)$ resulting from the collision process were detected by making coincidence measurements between the $\mathrm{Ly}\ensuremath{-}\ensuremath{\alpha}$ photon emitted in the decay of the $2p$ state and the resultant fast neutral particle. The probability of transfer to the state $\mathrm{H}(2p)$, ${P}_{2p}$, is presented for ${\mathrm{H}}^{+}$ + Ar for the condition $\ensuremath{\Theta}T=20$ keV deg, where $\ensuremath{\Theta}$ is the scattering angle and $T$ the incident-ion kinetic energy, which represents an impact parameter of 0.53 a.u. For the ${\mathrm{H}}^{+}$ + He system a comparison between experimental results for ${P}_{2p}$ and the many-state calculation of Sin Fai Lam shows the theory to overestimate ${P}_{2p}$ by an order of magnitude for $\ensuremath{\Theta}T=20$ keV deg as well as for measurements where the impact parameter varied from 0.05 to 0.25 a.u.