HR: 1330h
AN: SA12A-1077    [PDF]
TI: High-Temperature Ultrahigh-Resolution Absorption Cross Section Measurements of O2 in the 91.1-91.8 nm Region
AU: * Wu, R C
EM: robertwu@usc.edu
AF: University of Southern California, Space Sciences Center, SHS 270, Los Angeles, CA 90089-1341 United States
AU: Judge, D L
EM: djudge@usc.edu
AF: University of Southern California, Space Sciences Center, SHS 270, Los Angeles, CA 90089-1341 United States
AU: Matsui, T
AF: Hiroshima University, Hiroshima Synchrotron Radiation Center, Kagamiyama, Hir 739-8526 Japan
AB: The NII 108.5 nm, NII 91.7 nm, and the OII 83.4 nm are the prominent emission in the EUV airglow. The atmospheric extinction due to absorption by molecular N2 and O2 strongly affects the observed airglow emission fluxes. Since the temperature of the upper atmosphere of the Earth can be as high as 900 K it is important to know all relevant molecular cross sections at such temperatures. Therefore, the high-temperature ultrahigh-resolution photoabsorption cross section measurements of N2 and O2 in the extreme ultraviolet (EUV) region are important to their atmospheric modeling implications. A temperature change on a gaseous sample clearly will affect the Doppler broadened linewidth and the rotational and vibrational population distributions of the ground electronic state from which absorption takes places. The consequences of such a change are the enhancement or elimination of hot bands, the broadening or sharpening of rovibronic line shapes, the decreasing or increasing in cross section values of an absorption feature. In this poster we report ultrahigh resolution absorption cross section measurements of O2 with a resolution of 0.0008 nm in the 91.1-91.8 nm region at temperatures of 535 K and 295 K. The 6.65-m vertical off-plane Eagle spectrometer available at the Photon Factory, KEK, Tsukuba, Japan, was employed in the present study. The detailed temperature-dependent results of this work will be presented. This work is supported by NSF grant ATM-0096761.
DE: 0300 ATMOSPHERIC COMPOSITION AND STRUCTURE
DE: 0310 Airglow and aurora
DE: 0317 Chemical kinetic and photochemical properties
DE: 0343 Planetary atmospheres (5405, 5407, 5409, 5704, 5705, 5707)
DE: 0350 Pressure, density, and temperature
SC: SPA - Aeronomy [SA]
MN: 2003 Fall Meeting