ROTATIONAL COLLISIONAL PROCESSES IN $CH_{3}CI$

$^{1}$ H.O Everitt and F.C. De Lucia J. Chem. Phys. 90 , 3520(1989).Author Institution: Department of Physics, Duke University; Department of Physics, Ohio State University; Department of Physics, U.S. Army Research Office Research Triangle ParkWe have used time-resolved infrared/mm-wave double resonance techniques to observe a $\Delta K=3n$ process in the methyl $halides^{1}$ theat equilibrates the rotational state populations belonging to the same symmetry type within a vibrational state. Recently, in the case of $v_{6} = 1 CH_{3}Cl$, we have observed changes in both the I-type doubling quantum number as well as K. These processes are found to be quite rapid, with cross sections on the order of gas kinetic collisions. For the earlier work on $CH_{3}F$, no deviation from an ambient Boltzmann distribution was found for the population transferred by the $\Delta K=3n$ process. In contrast, the $CH_{3}CI$ data shows distinctly non ambient affects that depend on the energy of the pumped state relative to the ambient kinetic energy. Samples from a large set of data encompassing different pumped states and a number of rotational states will be presented and discussed