EXCITATION MECHANISMS IN THE HCN FIR $LASER^{*}$

Author Institution: Department of Physics, Duke University Durham; Department of Chemistry, California institute of Technology Pasadena; Department of Physics, University of New Brunswick Fredericton; Department of Physics, Duke University DurhamA number of excitation mechanisms have been proposed to explain the behavior and efficiency of the HCN FIR laser. We have used millimeterwave spectroscopic techniques to probe this excitation. The effects due to the addition of CO on the distribution of vibrational excitation and laser efficiency have been studied. We have also observed the concentration of proposed chemical precursors, including the free radical CN. A spectroscopic study of $^{2}\Sigma$ CN is also reported. 65 new lines in the first 4 vibrational states have been measured. A simultaneous non-linear least squares fit of these data, along with those previously reported by Dixon and $Woods^{1}$, has been carried out. $^{*}$ Work supported by ARO Grant DAAG-29-80-C-0026 and NASA Grant NAGW-189. $^{1}$T.A. Dixon and R. C. Woods, J. Chem. Phys. 67, 3956-3964 (1977)