Chemical pumping of pure rotational HF lasers

Pure rotational laser oscillation has been observed in HF following flash photolysis of various mixtures of trifluoromethyl halide, acetylenic compound, and argon in the ration of 1:1:100. Specifically, mixtures of CF3I+C2H2, CF3I+CH3C2H, and CF3Br+C2H2 exhibit different patterns of laser intensity, and, further, are markedly different from patterns generated by the known photoelimination system CH2CF2. The above systems show laser intensity at lower rotational levels than could be explained by simple V→R collision induced mechanisms (as in the case of CH2CF2). Further, the intensities in these anomalously low rotational levels appear to be a function of the identity of the electronically excited halide (I or Br) produced photolytically. A computer simulation model has been constructed which relaxes nascent HF through V→R transfer (formed vibrationally and rotationally excited by elimination) but incorporates an additional pumping mechanism, that of quenching of I or Br by these relaxing HF molecules. Most of the experimentally observed laser intensities are explained on the basis of this new pumping mechanism.