The authors report the observation of stimulated Stokes scattering of 5.3 mu m pump radiation by spin flip excitations in InSb, using a 10.6 mu m CO₂ laser, together with a tellurium frequency doubler, as the 5.3 mu m source. The effects of resonant enhancement on the 5.3 mu m scattering are discussed and comparison made with 10.6 mu m results. The observation of atmospheric water vapour absorption lines near 5.5 mu m demonstrates the application of the spin flip source to high resolution spectroscopy.