Emission of simultaneous tunable off-resonance and line centre FIR Raman lines in NH3 and CH3F

By pumping with a continuously tunable CO2 laser we have analysed the FIR emission of the sR(3,0) ammonia line and the lambda=2 mm emission of the R(1) CH3F absorption line. The simultaneous emission of an off-resonance tunable Raman frequency and an untuned line centre one has been observed. The results agree with the theory. In addition about 8% tuning of the mean FIR frequency was observed at 150 GHz