Absolute differential and integral electron excitation cross sections for the O sub 2 (a sup 1. Delta. sub g l arrow X sup 3. Sigma. sub g sup minus ) transition

Journal Article · Sat Aug 01 00:00:00 EDT 1992 · Journal of Geophysical Research; (United States)

DOI:https://doi.org/10.1029/92JA00873· OSTI ID:7172945

Doering, J P ^[1]

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1. Johns Hopkins Univ., Baltimore, MD (United States)

Differential and integral electron excitation cross sections for the O{sub 2} a{sup 1}{Delta}{sub g} {l arrow} X{sup 3}{Sigma}{sub g}{sup {minus}} transition at 0.97 eV have been measured as a function of incident electron energy from 2.6 to 28.6 eV. Differential cross sections (DCS) for the a{sup 1}{Delta}{sub g} state were measured relative to elastic scattering as a function of scattering angle at each incident energy for the angular range 20{degree}-134{degree}. At incident energies between 7 and 18 eV, it was necessary to use a synthetic spectrum program to separate the a{sup 1}{Delta}{sub g} {l arrow} X{sup 3}{Sigma}{sub g}{sup {minus}} band intensity from intense vibronic excitation of the O{sub 2} ground state. The relative DCS values were converted to absolute values using the elastic scattering cross-section values of Trajmar et al. (1971) up to 90{degree} and revised values at higher angles. The DCS results, which show the typical weak dependence on scattering angle of an optically forbidden transition, are in satisfactory agreement with previous measurements. The DCS were integrated to give integral cross sections at each incident energy. The results are in excellent agreement with previous measurements and help to establish the a{sup 1}{Delta}{sub g} {l arrow} X{sup 3}{Sigma}{sub g}{sup {minus}} transition cross section as a valuable secondary standard for the measurement of electron excitation cross sections in unstable species such as atomic oxygen.

• OSTI ID: 7172945
• Journal Information: Journal of Geophysical Research; (United States), Journal Name: Journal of Geophysical Research; (United States) Vol. 97:A8; ISSN JGREA; ISSN 0148-0227
• Country of Publication: United States
• Language: English

Related Subjects

661320* -- Auroral
Ionospheric
& Magnetospheric Phenomena-- (1992-)
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
AURORAE
COLLISIONS
CROSS SECTIONS
DATA
DIFFERENTIAL CROSS SECTIONS
ELASTIC SCATTERING
ELECTRON COLLISIONS
ELECTRON-MOLECULE COLLISIONS
ELEMENTS
ENERGY-LEVEL TRANSITIONS
EXCITATION
EXPERIMENTAL DATA
INFORMATION
INTEGRAL CROSS SECTIONS
MOLECULE COLLISIONS
MOLECULES
NONMETALS
NUMERICAL DATA
OXYGEN
SCATTERING