Far-infrared laser emission from deuterated ammonia

By optically pumping the deuterated isotopomers, of (NH3)-N-14 and (NH3)-N-15 using (CO2)-C-12-O-16, (CO2)-C-13-O-16, (CO2)-C-12-O-18, and (CO2)-C-13-O-18 lasers, several new far-infrared (FIR) emission lines between 65 mum and 125 mum have been detected. The existing spectroscopy of N-14-ammonia isotopomers has been used to identify many of these lines, as well as some previously observed but unidentified. The spectroscopic data have been analyzed to predict over 20 additional FIR laser lines that could be pumped by a more capable CO2 laser. This effort was motivated by a need for strong laser lines in frequency coincidence with molecular transitions of astrophysical interest. Of particular note is the measurement of the 2680-GHz line of (NHD2)-N-14, whose frequency is 4.9 GHz higher than that of the important J = 1 - 0. line-of interstellar HD.