Knowledge Bank

We report the infrared measurement of rotational and translational temperatures for $CH3F$ in the gas phase with a temperature of 16 Kelvins. This is accomplished by extending the collisional cooling technique originally developed for the microwave spectral $region1$ to the infrared. We measured an RQ(J,0) feature centered at approximately 1475 wavenumbers (in $cm-1$) in the V2 and V5 bands of $CH3F$. The rotational temperature was determined by measuring relative intensities of low J transitions and comparing these results to those predicted by the rotational partition function. We utilized measurements of the absorption line width to calculate the translational temperature.