Atomic oxygen P-3 -> S-3(0) (lambda 1304 angstrom) transition revisited: Cross section near threshold

Citation
Jp. Doering et J. Yang, Atomic oxygen P-3 -> S-3(0) (lambda 1304 angstrom) transition revisited: Cross section near threshold, J GEO R-S P, 106(A1), 2001, pp. 203-209
Citations number
17
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Space Sciences
Journal title
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
ISSN journal
2169-9380 → ACNP
Volume
106
Issue
A1
Year of publication
2001
Pages
203 - 209
Database
ISI
SICI code
0148-0227(20010101)106:A1<203:AOP-S(>2.0.ZU;2-5
Abstract
The direct excitation cross section for the atomic oxygen P-3 --> S-3(0) tr ansition (lambda 1304 Angstrom) has been measured at four incident energies between 13.4 and 40 eV. These measurements were made to add sufficient det ail to previous direct excitation measurements to allow the near-threshold cross section to be determined. Previous optical measurements of the 1304 A ngstrom emission cross section disagree by up to a factor of 2 in this impo rtant energy region. We have also compared the atomic hydrogen e + H(1s) -- > H(2s + 2p) cross section, used previously as a secondary standard for our direct excitation measurements of atomic oxygen cross sections, to recent measurements of the total e + H --> Lyman alpha cross section and have foun d agreement at the +/-15% level, making a revision of our previously report ed atomic oxygen cross sections unnecessary. The new direct excitation atom ic oxygen cross section results, combined with previous measurements, suppo rt the emission cross section measured by Stone and Zipf [1974] and revised by Zipf and Erdman [1985] over the measurement of Wang and McConkey [1992] . Except for the region just above threshold at 10-25 eV incident energy, a ll the cross section measurements now agree to within +/-20%. The 100 eV va lue of the atomic oxygen P-3 --> S-3(0) emission cross section from a combi nation of the emission and direct excitation cross section experiments is 8 .6 +/- 11% x 10(-18) cm(2).