Formation of H(2p) and H(2s) in Collisions of 1-25 keV Hydrogen Atoms with the Rare Gas.
Rept. for Aug 70-Jul 71,
AEROSPACE CORP EL SEGUNDO CALIF LAB OPERATIONS
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Cross sections have been measured for the emission of Lyman-alpha radiation in collisions of 1-25 keV hydrogen atoms with He, Ne, Ar, Kr and Xe owing to excitation of the fast atom to the 2p and 2s states. The intensity of Lyman-alpha emitted spontaneously from collisionally-excited H2p was measured at 54.7 deg. or 125.3 deg. with respect to the H beam in an essentially field-free collision chamber with an oxygen-filtered photometer calibrated by reference to previous results for H on Ar. After a small correction for cascade effects the data yield the cross sections for population of the 2p state in these collisions. An electric field, oriented in the direction of the beam, was applied within the collision chamber to quench collisionally excited H2s, and the resulting increase in Lyman-alpha radiation has been used to derive the cross sections for formation of the 2s state. The results are compared with previous measurements made at higher energies and with theoretical estimates of these cross sections. The present extension of previous results to lower energy has revealed new structure in the energy dependence of the cross sections for the heavier targets. Existing theoretical treatments of these collisions fail to yield either the magnitude or energy dependence of the cross sections at energies below 5 keV. Author
- Atomic and Molecular Physics and Spectroscopy