On the assignment of optically pumped far-infrared laser emission from CH3OH

Progress in the analysis of the Infrared spectrum of CH,OH in the 930-1450 cm(-1) region has led to assignments, confirmations, or new insights for a number of far-infrared laser (FIRL) transition systems optically pumped by CO2 lasers. Many of the systems involve FIRL transitions among the CO-stretching, CH3-rocking, OH-bending, and CH3-deformation vibrational modes, giving useful information on the torsion-rotation structure of the methanol vibrational energy manifold. Some anomalies and mysteries concerning the identity of the lasing levels have been resolved, but several new ones have arisen. Altogether, 45 CH3OH IR-pump/FIR-laser systems are examined in light of the new spectroscopic information; about half of the system assignments are new and half have been previously reported in the literature and are here confirmed, extended, or revised. (C) 1999 Academic Press.