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Abstract
Electrons ejected from atomic and molecular hydrogen in He$\sp+$ ion impacts were observed with projectile energies ranging from 30 to 120 keV. The ejection angles observed were $15\sp\circ, 30\sp\circ, 50\sp\circ, 70\sp\circ, 90\sp\circ, 110\sp\circ, 130\sp\circ$ and 160$\sp\circ$ with electron energies ranging from 1.5 to 130 eV. Ejected electrons were energy analyzed by an electrostatic analyzer with 5% resolution and were detected by a channel electron multiplier.
A Slevin-type RF hydrogen atom source was used to generate a mixed target of atomic and molecular hydrogen. The dissociation fraction of the target was determined from the measurement of 9-eV H$\sp+$ ions coming from the break-up of the 2p$\sigma\sb{\rm u}$ state of the H$\sb2\sp+$ molecular ion. Methods were devised to extract the electron ejection cross section ratio between hydrogen atoms and molecules. Cross sections for the hydrogen atom were then calculated from additional measurements on pure H$\sb2.$
The results are compared to plane-wave-Born approximation (PWBA) calculations, classical-trajectory-Monte-Carlo (CTMC) calculations, and continuum-distorted-wave-eikonal-initial-state (CDW-EIS) calculations for proton impact. Electron loss cross sections are calculated with PWBA and used as a correction to the above calculations.
