# J-AND K-CHANGING ROTATIONAL COLLISIONAL PROCESSES IN $CH_{3}Cl$

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 Title: J-AND K-CHANGING ROTATIONAL COLLISIONAL PROCESSES IN $CH_{3}Cl$ Creators: Pape, T. W.; De Lucia, Frank C.; Skatrud, David D. Issue Date: 1993 Publisher: Ohio State University Abstract: We have used time-resolved infrared/mm-wave double resonance techniques to study rotational and vibrational collisional processes in methyl chloride. As was the case with $CH_{3}F_{1}$, the dipole-dipole process in $CH_{3}Cl$ has the largest cross section, and the $\Delta J = n, \Delta K = 0 (n \geq 2)$ processes are well described by a two parameter Statistical Power Gap Law (SPG). In addition, we have measured a rapid $\Delta K = 3n$ thermalizing processes in $v_{6} = 1$ of $CH_{3}Cl$ similar to that observed in $v_{3} = 1$ of $CH_{3}F^{2}$. However, the $\Delta K = 3n CH_{3}Cl$ data exhibited a feature distinct from that of the $CH_{3}F$. Whereas the $\Delta K = 3n$ process populates the $CH_{3}F$ final states with an ambient temperature Boltzmann distribution, it populates the $CH_{3}Cl$ states with an initially nonambient Boltzmann distribution. This initial temperature is related to the energy of the rotational state populated by the $CO_{2}$ laser pump, and its relaxation rate is related to the rate that the $\Delta K = 3n$ process populates the A symmetry (the pumped symmetry) states. The $CH_{3}Cl$ and $CH_{3}F$ results will be reconciled. Description: $^{1.}$ H. O. Everitts and F. C. De Lucia, J. Chem. Phys. 92, 6480 (1990). $^{2.}$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 URI: http://hdl.handle.net/1811/18535 Other Identifiers: 1993-RE-10