Gain measurements in stimulated rotational Raman scattering in para hydrogen.

The dependence on CO(2)-laser pump energy of the output Stokes radiation obtained through stimulated rotational Raman scattering in para hydrogen is studied experimentally. The effective plane-wave gain for this process was determined as a function of the scattered wavelength by using a theoretical expression for the scattered pulse energy. Experimental values for the gain follow an inverse-wavelength law and are in close agreement with theory.