Far-infrared laser-emission spectroscopy on ammonia isotopomers

In this paper we report the investigation of the isotopic ammonia gases14NH3,14NH2D,14NHD2,15NH3 and15ND3 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.

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