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 $\mathrm{H}\mathrm{}\left(2p\right)\mathrm{}$ resulting from the collision process were detected by making coincidence measurements between the $\mathrm{Ly}-\alpha$ photon emitted in the decay of the $2p$ state and the resultant fast neutral particle. The probability of transfer to the state $\mathrm{H}\mathrm{}\left(2p\right)\mathrm{}$, $P_{2p}$, is presented for ${\mathrm{H}}^{+}$ + Ar for the condition $\Theta T=20\mathrm{}$ keV deg, where $\Theta$ 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 $\Theta T=20\mathrm{}$ keV deg as well as for measurements where the impact parameter varied from 0.05 to 0.25 a.u.