With the addition of six newly discovered lines, only four pumped media (CH3OH, CH3OD, CD3OD, and CH2CF2) are needed to cover the range 8 to 244 cm-1 densely for submillimeter laser spectroscopy. The 35 reported lines have powers far exceeding those available in conventional blackbody sources and provide an average spacing comparable with that found in Fourier spectrometers. The new lines were found in CH3OD at 24.0,30.3,43.6,74.2, and 214.1 cm-1 and in CH2CF2 at 13.1 cm-1.
B. L. Bean and S. Perkowitz, "Complete frequency coverage for submillimeter laser spectroscopy with optically pumped CH3OH, CH3OD, CD3OD, and CH2CF2," Opt. Lett. 1, 202-204 (1977)