A study of the methanol laser with a 500 MHz tunable CO2 pump laser

Rotation–torsion–vibration term-value mapping for CH3OH: Torsion-mediated doorways and corridors for intermode population transfer

“…The mixing induced by many of the interactions among the upper vibrational states has been an important factor in the generation of far-infrared laser emission from CH 3 OH by optical pumping with CO 2 lasers [10,[27][28][29][30][31]. Numerous infrared pump transitions have acquired sufficient strength through intensity-borrowing due to the mixing to transfer significant population into relatively ''dark'' upper states such as the CH 3 -rocking modes and thereby generate a wide range of FIR laser lines within those states.…”

“…This small DK = 3 resonance affects the Q(21) line of the (A, co, 2, 4) ‹ (A, gr, 2, 4) subband that is the pump transition for the 9P(36) + 184 MHz FIR laser system [29,30], and pushes it up and away from the 9P(36) CO 2 line center. We should note here that the assignment of the single 64.397 lm FIR laser line as the (A, co, 2, 4, 21) fi (A, co, 1, 3, 21) transition was mistakenly claimed to be new in [29] but was actually first assigned by Mukhopadhyay et al [31].…”

“…Several of them play a significant role in optically pumped FIR laser emission from CH 3 OH [27][28][29][30][31], and the observed FIR laser frequencies in fact provided critical clues to the original assignments and origin of the perturbations for a number of the FIR laser transition systems. This is analogous to the resonance observed previously for the 13 CH 3 OH isotopomer [22] but here occurs between J 0 = 28-29 for the A À components of the asymmetry doublets rather than J 0 = 21-22 for the A + components in 13 CH 3 OH, due to the downward shift of the CO-stretching mode for the C-13 species.…”