HR: 1330h
AN: SA12A-1073    [PDF]
TI: Vibrational Distributions in the {\it A}$^{3}\Sigma^{+}_{u}$ and {\it A'}$^{3}\Delta_{u}$ States of O$_{2}$ in the MLT Nightglow: Results from Astronomical Sky Spectra
AU: * Widhalm, A M
EM: widhalm@usc.edu
AF: Department of Physics and Astronomy, University of Southern California, Los Angeles, CA 90089 United States
AU: Slanger, T G
EM: tom.slanger@sri.com
AF: Molecular Physics Laboratory SRI International, 333 Ravenswood Ave., Menlo Park, CA 94025 United States
AU: Cosby, P C
EM: philip.cosby@sri.com
AF: Molecular Physics Laboratory SRI International, 333 Ravenswood Ave., Menlo Park, CA 94025 United States
AU: Huestis, D L
EM: david.huestis@sri.com
AF: Molecular Physics Laboratory SRI International, 333 Ravenswood Ave., Menlo Park, CA 94025 United States
AB: Astronomical sky spectra from the Keck I telescope on Mauna Kea have been used to obtain vibrational distributions in the O$_{2}${\it A}$^{3}\Sigma^{+}_{u}$ and O$_{2}${\it A'}$^{3}\Delta_{u}$ states from rotationally-resolved Herzberg I {\it A-X} and Chamberlain {\it A'-a} band emissions in the terrestrial nightglow. The {\it A}$^{3}\Sigma^{+}_{u}$ distribution is similar to that presented in earlier publications, with the exception that there is significant population in the previously undiscerned v = 0 level. For the {\it A'}$^{3}\Delta_{u}$ state, the vibrational distribution is essentially the same as that of the {\it A}$^{3}\Sigma^{+}_{u}$ state when comparison is made in terms of the level energies. The intensity ratio at the peak of the distribution favors the {\it A-X} emission by a factor of four, as previously shown, and is probably a measure of radiative efficiency. The peaks in both population distributions are about 0.25 eV below the O($^{3}$P) + O($^{3}$P) dissociation limit, and reflect both the pathways by which the nascent O$_{2}$* molecule is generated and stabilized, and the collisional loss rates.
DE: 0310 Airglow and aurora
DE: 0355 Thermosphere--composition and chemistry
DE: 0358 Thermosphere--energy deposition
SC: SPA - Aeronomy [SA]
MN: 2003 Fall Meeting