Electron Capture into the4sState of H by FastH+Impact on Gases

Abstract

Cross sections have been determined for electron capture into the $4s$ state of atomic hydrogen by fast-proton (5-120-keV) impact on He, Ar, Ne, ${\mathrm{H}}_2$, ${\mathrm{H}}_2$, and ${\mathrm{O}}_2$. Some improved measurements are reported on previously published cross sections for electron capture into the $3s$ state of atomic hydrogen for fast-proton impact on these gases. Above 80 keV, the cross sections for capture into the $3s$ and $4s$ states appear to be proportional to $n^{-3\mathrm{}}$, where $n$ is the principal quantum number of the final state. Secondary structure appears in the $3s$ and $4s$ excitation functions for impact on the heavier gases (Ar, Ne, ${\mathrm{N}}_2$, and ${\mathrm{O}}_2$) below 7 keV.