Vacuum ultraviolet photochemistry of CH{sub 4} and isotopomers. II. Product channel fields and absorption spectra

Journal Article · Fri Sep 08 04:00:00 EDT 2000 · Journal of Chemical Physics

DOI:https://doi.org/10.1063/1.1288145· OSTI ID:20217439

Wang, Jen-Han ^[1]; Liu, Kopin ^[1]; Min, Zhiyuan ^[2]; Su, Hongmei ^[2]; Bersohn, Richard ^[2]; Preses, Jack ^[3]; Larese, John Z ^[3]

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1. Institute of Atomic and Molecular Science (IAMS), Academia Sinica, Taipei (Taiwan)
2. Department of Chemistry, Columbia University, New York, New York 10027 (United States)
3. Chemistry Department 555A, Brookhaven National Laboratory, Upton, New York 11973 (United States)

In part I of this work the relative velocities and anisotropies of the atomic H and D fragments from methane photolysis at 10.2 eV were measured. In this paper the relative abundance of the methyl and methylene fragments are reported. A complete set of quantum yields for the different photodissociation channels of each isotopomer is obtained by combining the two sets of data. Previously it was found that H atoms are almost four times more likely than D atoms to be ejected; now it is found that hydrogen molecule photofragments are much richer in H atoms than in D. Overall, the heavier D atoms are more likely than the H atoms to remain attached to the carbon atom. An implication for astrophysics is discussed. The VUV absorption spectra of CH{sub 4} and CH{sub 3}D are almost identical both at room temperature and 75 K. There is, as expected, no variation in the absorption spectrum with temperature. Evidence is given that all or almost all of the methylene is produced in the a {sup 1}A{sub 1} and not in the ground {sup 3}B{sub 1} state. (c) 2000 American Institute of Physics.

• OSTI ID: 20217439
• Journal Information: Journal of Chemical Physics, Journal Name: Journal of Chemical Physics Journal Issue: 10 Vol. 113; ISSN JCPSA6; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
ABSORPTION SPECTRA
DEUTERIUM COMPOUNDS
EXPERIMENTAL DATA
FAR ULTRAVIOLET RADIATION
FRAGMENTATION
METHANE
PHOTOCHEMICAL REACTIONS
PHOTOLYSIS