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Rovibrational energy transfer from the (0/sup 0/, K' = 0) and (7/sup 2/,K' = 0) levels of S/sub 1/ glyoxal in crossed beam collisions with H/sub 2/

Journal Article · · J. Chem. Phys.; (United States)
OSTI ID:6918818

Crossed molecular beams have been used to study rotationally and vibrationally inelastic scattering from the (7/sup 2/, K' = 0) and the (0/sup 0/, K' = 0) levels of /sup 1/A/sub u/ (S/sub 1/) trans-glyoxal in collision with H/sub 2/. The center-of-mass collision energy was approximately 80 meV (650 cm/sup -1/). Laser excitation was used to select each of the initial vibrational levels with rotational states limited to J' = 0--10, K' = 0. Dispersed fluorescence was used to monitor quantitatively the final rotational and vibrational levels populated in single collision scattering. Vibrationally inelastic scattering from each initial level has an absolute cross section large enough to allow the process to be observed easily with resolution of accompanying ..delta..K rotational state changes. Although many final vibrational levels are energetically accessible and in principle observable, only those reached by +- 1 quantum changes in the lowest frequency mode, the OHC--CHO torsion ..nu../sub 7/, are seen. From the initial level 7/sup 2/, the cross sections for ..delta..upsilon/sub 7/ = +1 and ..delta..upsilon/sub 7/ = -1 are nearly identical, mirroring the symmetry of UP and DOWN vibrational transitions recently observed in I/sup *//sub 2/ inelastic scattering from H/sub 2/, D/sub 2/, and He. The total cross section for pure rotationally inelastic scattering from 0/sup 0/ is about nine times larger than that for rovibrationally inelastic scattering, whereas the two cross sections are nearly equivalent for 7/sup 2/.

Research Organization:
Department of Chemistry, Indiana University, Bloomington, Indiana 47405
OSTI ID:
6918818
Journal Information:
J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 89:8; ISSN JCPSA
Country of Publication:
United States
Language:
English