Laser oscillation at 337 and 311 ..mu..m has been obtained from HCN molecules prepared in vibrationally excited states by the reaction between cyanogen radicals and hydrogen molecules. It has likewise been observed in HCN raised to an electronically excited state by flash photolysis. The characteristics of the pulsed output are quite different in the two cases and beginnings have been made on experiments to probe the pumping and energy transfer kinetics. The rate determining step is not the reaction rate, but rather some relaxation process that eventually channels the excitation into the upper lasing state of one quantum each of CN stretch and bend. Detailed studies of the relative intensities of pure rotational lasing in OH and OD have been made. The rotational inversions are produced by rare gas-aided, adiabatic energy conversion from vibrational to rotational excitation. The process is rapid in comparison to rotational collisional relaxation. Using transfer parameters from the ''information theoretic'' analysis (R. D. Levine) computations have been made which reproduce the results in detail, providing support for the pumping mechanism proposed, and the applicability of the theory. Preliminary work on NH (from the HN/sub 3/ photolysis) has opened up extremely interesting questions concerning the electronic states …