Accession Number : AD0739184

Title :   Cross Sections for Emission of Lyman-Alpha Radiation in Collisions of 1-25 keV Protons and Hydrogen Atoms with Constituents of Planetary Atmospheres.

Descriptive Note : Rept. for Jul-Nov 71,

Corporate Author : AEROSPACE CORP EL SEGUNDO CALIF LAB OPERATIONS

Personal Author(s) : Birely,John H. ; McNeal,Robert J.

Report Date : 31 JAN 1972

Pagination or Media Count : 23

Abstract : Cross sections are reported for emission of Lyman-alpha radiation in collisions of a charge-equilibrated 1-25 keV hydrogen beam with N2, O2, CO, CO2, NH3, CH4, and H2. For each target molecule, the separate cross sections for formation of H(2p) and H(2s) in H(+) and H collisions and the fractional population of these projectiles in a charge-equilibrated beam are used to calculate the effective cross section for formation of H(2p) and H(2s). Individual contributions to the overall Lyman-alpha intensity owing to projectile and dissociative excitation are presented for the hydrogen-containing compounds. The results show that, for both projectile and dissociative excitation, collisions involving impact of fast hydrogen atoms rather than protons are the major source of Lyman-alpha production in an aurora. Projectile excitation is demonstrated to be a substantially more important source of Lyman alpha than dissociative excitation in the 1-25 keV energy range. (Author)

Descriptors :   (*AURORAE, HYDROGEN), (*HYDROGEN, EMISSIVITY), PROTON BOMBARDMENT, NITROGEN, OXYGEN, CARBON MONOXIDE, CARBON DIOXIDE, AMMONIA, METHANE, EXCITATION

Subject Categories : Atmospheric Physics
      Atomic and Molecular Physics and Spectroscopy

Distribution Statement : APPROVED FOR PUBLIC RELEASE