Resonant stimulated Raman scattering in NH3 characterized by pump radiation depletion and a wide frequency tuning range

Concurrent resonance stimulated Raman scattering (RSTRS) of radiation from a CO₂ laser was observed in NH₃ for the Gs(5, 0) → 1ν₂s(5, 0) transition. Four new lasing lines were observed in the wavelength range 67 μm. The tuning range in the far infrared was 4.5 cm^–1. The power of infrared radiation reached 2 MW for a quantum efficiency of the process 36%. Depletion of the pump radiation, time dependence of the process, and forward–backward asymmetry of RSTRS were observed. A study was made of the difference between the RSTRS characteristics for one and three passes through a multipass cell. The stimulated Raman scattering thresholds were different for linear and circular pump polarizations.