Accession Number : AD0609168

Title :   MEASUREMENT OF ATOMIC COLLISION CROSS SECTIONS.

Descriptive Note : Final rept. for 1 Dec 58-30 Nov 64,

Corporate Author : GENERAL DYNAMICS SAN DIEGO CALIF GENERAL ATOMIC DIV

Personal Author(s) : Stebbings,R. F.

Report Date : 27 NOV 1964

Pagination or Media Count : 58

Abstract : The production of Lyman-alpha radiation in H(+) -H (1s) collisions has been investigated. The cross sections for 1s-2p excitation of the thermal-energy-target H atoms, and for electron capture into the 2p state of the projectiles, have been determined separately. These measurements are of particular significance in that they provide experimental information on a heavy-particle inelastic collision, involving only one electron, in which the states of all interacting particles are determined. Comparison with the results of calculation subjects the validity of the scattering approximations to direct scrutiny. It appears that the low energy behavior for both excitation and capture is adequately represented by theory as is the highenergy behavior for electron capture. The calculations appear to over-estimate the cross section for 1s-2p excitation by about a factor of 2 at the high energies. Electron impact ionization of molecular oxygen was investigated in the immediate vicinity of threshold using electron beams of high energy-resolution. The results suggest that a re-evaluation of the mechanism of the ionizing process may be necessary.

Descriptors :   (*ATOMIC STRUCTURE, MEASUREMENT), (*ELECTRONS, EXCITATION), (*UPPER ATMOSPHERE, GAS IONIZATION), ATOMS, HYDROGEN, OXYGEN, NITROGEN, PHOTONS, IONS, SCATTERING, IONIZATION POTENTIALS, IONIZATION, POLARIZATION, ELECTRON CAPTURE, SPACE ENVIRONMENTS

Distribution Statement : APPROVED FOR PUBLIC RELEASE