Experimental investigation of mechanisms of parametric generation of stimulated Raman scattering components

The results are given of an experimental investigation of parametric processes which govern the structure of the angular distribution of the intensity of the second Stokes and two anti-Stokes components of the stimulated Raman scattering in liquid nitrogen. The investigation was made using a collimated pump beam with a large transverse cross section. The angular structure of the first Stokes component included a highly directional peak against the background of diffuse radiation. These conditions made it possible to observe simultaneously for the first time three types of parametric generation at the second Stokes frequency. The observed angular spectra of the Raman components were explained on the basis of the theory of parametric interactions between plane waves. The reliable interpretation of the angular spectra and the high experimental precision made it possible to correct and extend the long-wavelength edge of the dispersion curve of liquid nitrogen at T = 77 °K.