FAR-INFRARED LASER-EMISSION SPECTROSCOPY ON AMMONIA ISOTOPOMERS

In this paper we report the investigation of the isotopic ammonia gases (NH3)-N-14, (NH2D)-N-14, (NHD2)-N-14, (NH3)-N-15 and (ND3)-N-15 optically pumped by a continuously tunable 20 atm CO2-laser. We found 267 far-infrared emission lines, produced by both inversion and Raman processes, in the frequency range from 15 cm(-1) to about 250 cm(-1). 200 of these were observed for the first time. We obtained far-infrared Raman tuning ranges exceeding 3 cm(-1), photon conversion coefficients up to 12% and maximum output energies of 0.9 mJ. Furthermore, the optimum gas pressure, the polarization and the transient behavior of optically pumped ammonia have been investigated.