NEW FAR-INFRARED LASER LINES AND ASSIGNMENTS FOR (CH3OH)-C-13 METHANOL

The (CH3OH)-C-13 isotopomer of methanol has been reinvestigated as a s ource of far-infrared (FIR) laser emission by the use of the extended line coverage available from an efficient CO2 laser recently developed for optical pumping. With this system we have observed 19 new FIR las er Lines, pumped by 11 different CO2 transitions, with five of the pum p lines belonging to the new 9HP CO2 hot band. Accurate heterodyne fre quency measurements of the FIR laser and the pump offset have been mad e for 16 FIR laser lines, including three previously reported in the l iterature. High-resolution Fourier-transform spectroscopic results for the GO-stretching and the CH3-rocking infrared fundamentals of (CH3OH )-C-13 have been applied to assign the pump and lasing lines for five of the transition systems. One system has the novel feature that two d ifferent CO2 pump lines excite the same upper level, and hence two FIR laser lines of the identical frequency are observed for two different pump lines. (C) 1995 Optical Society of America