Vibration. -->. vibration energy transfer in methane
Vibrational energy levels of methane in the range 2800 to 6000 cm/sup -1/ were excited by a pulsed tunable laser. Infrared fluorescence decays were observed at 294 K and analyzed to yield V..-->..V energy transfer pathways and rates. Symmetric stretching excitation is converted to asymmetric stretching in the same molecule with a rate constant k/sub 1/3.6=(plus-or-minus0.9) x 10/sup -11/ cm/sup 3/ molecule/sup -1/ s/sup -1/ (P=0.09). The ..nu../sub 2/ and ..nu../sub 4/ bending vibrations are interconverted somewhat less rapidly. Stretching excitation is converted to bending with a rate constant of (0.8 +- 0.2) x 10/sup -11/ cm/sup 3/ molecule/sup -1/ s/sup -1/ (P=0.022) for the stretching fundamentals and about twice that for overtone or combination levels. The rate of almost exactly resonant transfer of a vibrational quantum from one molecule to another was about (1.8 +- 0.6) x 10/sup -11/ cm/sup 3/ molecule/sup -1/ s/sup -1/ (P=0.05) for transfer of a bending quantum from CH/sub 4/(2..nu../sub 4/) and about three times less for transfer of a stretching quantum.
- Research Organization:
- Department of Chemistry, University of California, Berkeley, California 94720
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 5319299
- Journal Information:
- J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 72:10; ISSN JCPSA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
Molecular & Chemical Physics-- Collision Phenomena
74 ATOMIC AND MOLECULAR PHYSICS
ALKANES
CRYOGENIC FLUIDS
ELECTROMAGNETIC RADIATION
ENERGY LEVELS
ENERGY TRANSFER
ENERGY-LEVEL TRANSITIONS
EXCITATION
EXCITED STATES
FLUIDS
FLUORESCENCE
HYDROCARBONS
INFRARED SPECTRA
LASER RADIATION
LUMINESCENCE
METHANE
ORGANIC COMPOUNDS
PULSE TECHNIQUES
RADIATIONS
SPECTRA
VIBRATIONAL STATES