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Reaction and reorientation of electronically excited H{sub 2}(B) [electronic resource].

Published
Washington, D.C. : United States. Dept. of Energy, 1992.
Oak Ridge, Tenn. : Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy.
Physical Description
227 pages : digital, PDF file
Additional Creators
Lawrence Berkeley National Laboratory, United States. Department of Energy, and United States. Department of Energy. Office of Scientific and Technical Information
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Summary
The room temperature rate (TR) constants for fluorescence quenching fluorescence of H₂, HD, and D₂ B ¹Σ{sub u}⁺ by ⁴He were measured as a function of the initially excited rotational and vibrational level of the hydrogen molecule, and the RT rate constants for molecular angular momentum reorientation of H₂, HD and D₂ (B ¹Σ{sub u}⁺. v′=0, J′=1, M{sub J}=0) in collisions with He, Ne, Ar and H₂(X ¹Σ{sub g}⁺) were also measured. Vibrational state dependence of the quenching cross sections fits a vibrationally adiabatic model of the quenching process. From the vibrational state dependence of the quenching cross section, the barrier height for the quenching reaction is found to be 250±40 cm{sup −1}, and the difference in the H-H stretching frequencies between H₂(B) and the H₂-He complex at the barrier to reaction is 140±80 cm{sup −1}. The effective cross sections for angular momentum reorientation in collisions of H₂, HD, D₂ with He and Ne were found to be about 30 Ų and were nearly the same for each isotope and with He and Ne as collision partners. Cross sections forreorientation of HD and D₂ in collisions with Ar were 10.6±2.0 and 13.9±3.0 Ų, respectively. Reorientation of D₂(B) in collisions with room temperature H₂(X) occurs with a 7.6±3.4 Ų cross section. Calculated cross sections using semiclassical and quantum close coupled methods give cross sections for reorientation of H₂(B) and D₂(B) in collisions with He that agree quantitatively with experiment. Discrepancy between the calculated and experimental cross sections for HD(B)-HE are likely due to rotational relaxation in HD a Turbo PASCAL version of the data-taking program is included.
Report Numbers
E 1.99:lbl--33473
lbl--33473
Subject(s)
Other Subject(s)
Dissertation Note
Thesis (Ph.D.); PBD: Sep 1992
Note
Published through SciTech Connect.
09/01/1992.
"lbl--33473"
"DE93010435"
Pibel, C.D.
Funding Information
AC03-76SF00098
View MARC record | catkey: 13806296