Spectra Induced by Proton Impact on Helium

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 n¹S→2¹P(n=3, 4, 5), 3¹P→2¹S, and He ii(4{→}3) transitions. From these measurements cross sections have been estimated for excitation into the 3¹P, 3¹S, 4¹S, and 5¹S states, and for simultaneous ionization (including charge transfer) and excitation of helium into the $n=4$ state of He⁺.