DIODE LASER SPECTRUM OF THE $\nu_{9}$ FUNDAMENTAL BAND OF JET-COOLED $CH_{2}F_{2}$

Abstract

With strong absorptions suitable for $CO_{2}$ laser optical pumping in the $9\cdot 10 \mu m$ region of the spectrum, methylene fluoride, $CH_{2}F_{2}$, has received much attention as an important far-infrared laser medium. However, the high density of lines along with Coriolis and other perturbations have made it difficult to obtain a spectroscopic assignment for those energy levels responsible for FIR laser action. Utilizing a seeded, pulsed-jet expansion, we are able to obtain effective rotational and vibrational temperatures of approximately 5 K and 50 K, respectively, and thereby significantly simplify the spectrum in the region of the $\nu_{9}$ band origin at $1090 cm^{-1}$. Assignments are straightforward in the rotationally cold spectrum and the effects of perturbation made clearly obvious.