Absolute differential and integral electron excitation cross sections for atomic oxygen: 6. The /sup 3/P. -->. /sup 3/P and /sup 3/P. -->. /sup 5/P transitions from 13. 87 to 100 eV

Journal Article · Wed Jun 01 00:00:00 EDT 1988 · J. Geophys. Res.; (United States)

DOI:https://doi.org/10.1029/JA093iA06p05885· OSTI ID:6907597

Gulcicek, E E; Doering, J P; Vaughan, S O

We report the absolute differential and integral cross sections of the forbidden atomic oxygen /sup 3/P..-->../sup 3/P, 10.99 eV, and /sup 3/P..-->../sup 5/P, 10.76 eV, transitions for incident electron impact energies of 13.87 to 100 eV. These measurements are an extension of excitation cross section results that were reported previously at 30 eV incident energy by Gulcicek and Doering (1987). The differential cross sections (DCS) for the /sup 3/P..-->../sup 3/P transition are forward peaked, although not as strongly as for an electric dipole allowed transition and became flatter at the lower incident energies. The DCS for the /sup 3/P..-->../sup 5/P transition is roughly isotropic with scattering angle at all incident energies. The agreement between the /sup 3/P..-->../sup 3/P direct integral excitation cross section (ICS) and the experimental 8446 A emission cross section of Zipf, adjusted to remove cascade, is good over the entire energy range studied. The agreement with some, but not all, previous theoretical calculations for both transitions is satisfactory. The worst disagreement, roughly a factor of 2, is at the lowest incident energy, 13.87 eV, where the experimental results suggest that the ICS has begun to decrease toward threshold while the theoretical calculations show a continued increase. The ratio of the ICS for the /sup 3/P..-->../sup 3/P to the /sup 3/P..-->../sup 5/P transition varies from >6 at energies >30 eV to 22 at 13.87 eV. These ratios, which correspond directly to the 8446 A/7774 A emission line ratio in the thermosphere, allow conclusions to be drawn about the exciting electron energy distribution from the emission intensity ratio.

• Research Organization: Department of Chemistry, Johns Hopkins University, Baltimore, Maryland
• OSTI ID: 6907597
• Journal Information: J. Geophys. Res.; (United States), Journal Name: J. Geophys. Res.; (United States) Vol. 93:A6; ISSN JGREA
• Country of Publication: United States
• Language: English

Related Subjects

640304* -- Atomic
Molecular & Chemical Physics-- Collision Phenomena
74 ATOMIC AND MOLECULAR PHYSICS
ATOM COLLISIONS
COLLISIONS
CROSS SECTIONS
DIFFERENTIAL CROSS SECTIONS
EARTH ATMOSPHERE
ELECTRON COLLISIONS
ELECTRON-ATOM COLLISIONS
ELEMENTS
ENERGY RANGE
ENERGY-LEVEL TRANSITIONS
EV RANGE
EV RANGE 10-100
EXCITATION
FORBIDDEN TRANSITIONS
INTEGRAL CROSS SECTIONS
NONMETALS
OXYGEN
THERMOSPHERE