Spectra Induced by Proton Impact on Helium

Abstract

Spectra induced by proton impact on helium have been studied in the energy range of 20 keV to 130 keV. Absolute cross sections have been measured for helium emissions from $n{}_{}{}^1{}_{}{}^{}S\to 2{}_{}{}^1{}_{}{}^{}P(n=3, 4, 5)$, $3{}_{}{}^1{}_{}{}^{}P\to 2{}_{}{}^1{}_{}{}^{}S$, and He ii(4→3) transitions. From these measurements cross sections have been estimated for excitation into the $3{}_{}{}^1{}_{}{}^{}P$, $3{}_{}{}^1{}_{}{}^{}S$, $4{}_{}{}^1{}_{}{}^{}S$, and $5{}_{}{}^1{}_{}{}^{}S$ states, and for simultaneous ionization (including charge transfer) and excitation of helium into the $n=4\mathrm{}$ state of ${\mathrm{He}}^{+}$.