Formation of H(2p) and H(2s) atoms in collisions of 2-26 keV protons with hydrogen atoms

Abstract

A modulated crossed-beam technique has been used to determine cross sections for the four reactions: H⁺+H(1s) to H(2s or 2p)+H⁺ (electron capture) and H⁺+H(1s) to H⁺+H(2s or 2p) (excitation) within the energy range 2.3-26 keV. Results have been based on measurements, using a Doppler-shift identification technique, of the Lyman alpha radiation emitted from the beam intersection region both in the absence and in the presence of an electric field. While cross sections for excitation of the 2s state have not been reported previously, cross sections for capture into the 2s state agree well with those measured by Bayfield (1969a) using a furnace target technique. The H(2p) formation cross sections are also shown to be in reasonable accord with values based on the crossed-beam measurements of Stebbings et al. (1965).