Collision Induced Mode Selective Energy Transfer in Methylfluoride

  • R. Stender
  • J. Wolfrum
Part of the NATO ASI Series book series (NSSB, volume 105)

Abstract

After single quantum excitation of the C-F stretching vibration (υ3) in CH«F with a CO2 laser pathways for collision induced mode selective energy transfer into C-H bending and stretching modes were observed by laser induced infrared fluorescence. Until now, all the vibrational states of CH3F were assumed to come into V-V equilibrium with the pumped υ3 levels on the same time scale. The experiments reported here show that selective pathways with quite different time scales exist. In the case of pure CH3F, vibrational energy is transferred first via “up the ladder” processes in the pumped υ3 mode. Local coriolis resonances between 3 υ3 and υ4 at high J, K states can explain the fast, but not very efficient process
$${\text{C}}{{\text{H}}_3}{\text{F}}\left( {3{O_3}} \right) + C{H_3}F \rightleftarrows C{H_3}F\left( {{O_4}} \right) + C{H_3}F$$
which is suggested to be responsible for a partial filling of the C-H stretch vibrations (υ4). In a mixture of CH3F and rare gas atoms the intermode energy gaps between υ3, υ6, and υ2, υ5 are surmounted in collisions of the excited CH3F(υ3) molecule with rare gas atoms. Because υ1 and 2 υ5 are mixed by Fermi resonance, the V-V process leads directly to an efficient filling of the C-H stretch vibration (υ1)
$$2C{H_3}F\left( {{O_5}} \right) \rightleftarrows C{H_3}F\left( {2{O_5}} \right) + C{H_3}F$$

Keywords

Methane Manifold Argon Coherence Nism 

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Copyright information

© Plenum Press, New York 1984

Authors and Affiliations

  • R. Stender
    • 1
  • J. Wolfrum
    • 2
  1. 1.Max Planck-Institut für StrömungsforschungGöttingenGermany
  2. 2.Physikalisch-Chemisches InstitutRuprecht-Karls-Universität HeidelbergHeidelbergGermany

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