Far-Infrared Laser Assignments for Methylamine

Reported far-infrared laser lines for five different transition systems of CH3NH2 optically pumped by a CO2 laser have been identified spectroscopically through a high-resolution Fourier transform infrared study of the C-N stretching band together with CO2-laser/microwave-sideband broad-scan and Lamb-dip measurements. From the infrared analysis plus previous far-infrared (FIR) results for the ground vibrational state, quantum numbers have been assigned for seven methylamine FIR laser transitions and their C-N stretching pump absorptions coincident with the CO2 laser lines. The assignments are confirmed through the use of closed frequency combination loops that also provide improved FIR laser frequencies to spectroscopic accuracy.