Knowledge Bank

Time resolved millimeter/submillimeter wave - infrared double resonance techniques were used to study rotational energy transfer in methyl fluoride. A Q-switched $CO2$ laser pumped molecules into the $J=5,K=3,V3=1$ state of $\mathrm{<mrow\; data-mjx-texclass="ORD">13</mrow>}CH3F$, and the time response of many absorption lines in the $V3=1$ rotational manifold were monitored. An energy transfer map was obtained which includes state-to-state rates for two processes that change K-quantum number in addition to previously measured $\Delta J$ rates and vibrational relaxation rates. The first $\Delta K$ process, a vibrational swapping mechanism, effectively changes K in the $V3=1$ vibrational state through collisions of nonthermal molecules in $V3=1$ with thermal molecules in the ground vibrational state. The second is a direct collision induced transition and follows the selection rule $\Delta K=3n$. We have also obtained preliminary results on a similar study of $\mathrm{<mrow\; data-mjx-texclass="ORD">12</mrow>}CH3F$.