Absolute differential and integral electron excitation cross sections of the atomic oxygen sup 3 P and sup 5 P states at 30 eV
- Johns Hopkins Univ., Baltimore, MD (United States)
A new variable angle and incident energy electron energy loss spectrometer coupled to a supersonic jet expansion microwave discharge source has been constructed to study the electron scattering cross sections of stable and unstable atmospheric species. This apparatus was specifically designed to operate at low incident electron energies and at high scattering angles to observe forbidden transitions. In this paper the authors report the first measurements of the absolute differential and integral cross sections of the atomic oxygen (2p{sup 4} {sup 3}P-3p {sup 3}P), 10.99 eV, and (2p{sup 4} {sup 3}P-{sup 3}p{sup 5}P), 10.76 eV, transitions at a single electron impact energy of 30 eV. The direct excitation cross section ratio for the {sup 3}P and {sup 5}P states was found to be 6:1 which confirms previous suggestions that electron impact on O I is responsible for the observed 8446 {angstrom} and 7774 {angstrom} O I emissions in the dayside cusp region. Additional sources of O I 3p {sup 5}P are necessary to explain the nightside auroral 8446 {angstrom}/7774 {angstrom} ratio. The absolute cascade-free direct excitation integral cross sections for O I({sup 3}P-{sup 3}P) and O I ({sup 3}P-{sup 5}P) at 30 eV are 4.0 {times} 10{sup {minus}18} cm{sup 2} and 0.67 {times} 10{sup {minus}18} cm{sup 2}, respectively.
- OSTI ID:
- 5596309
- Journal Information:
- Journal of Geophysical Research; (United States), Journal Name: Journal of Geophysical Research; (United States) Vol. 92:A4; ISSN 0148-0227; ISSN JGREA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
Ionospheric
& Magnetospheric Phenomena-- (1992-)
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ATOM COLLISIONS
AURORAE
CHEMICAL COMPOSITION
COLLISIONS
CROSS SECTIONS
DATA
DIFFERENTIAL CROSS SECTIONS
EARTH ATMOSPHERE
ELECTRON COLLISIONS
ELECTRON-ATOM COLLISIONS
ELEMENTS
EMISSION SPECTRA
ENERGY LEVELS
ENERGY RANGE
ENERGY-LEVEL TRANSITIONS
EV RANGE
EV RANGE 10-100
EXCITATION
INFORMATION
INTEGRAL CROSS SECTIONS
MEASURING INSTRUMENTS
NONMETALS
OXYGEN
SPECTRA
SPECTROMETERS
THERMOSPHERE