Determination of vibrational matrix elements using heterodyne measurements of two-photon splittings in optically pumped molecular lasers

A new method for determining vibrational matrix elements in molecules absorbing CO₂ laser radiation is presented. The technique is based on the measurement of the forward gain doublet which arises in a totally Doppler-broadened three-level system interacting with two fields. The experiment is performed using high harmonic mixing in a Schottky diode and is shown to be independent of pump frequency offset. Experiments are performed on the 496-{μ}m CH₃F laser.