PARTIALLY COHERENT ANTI-STOKES-RAMAN SCATTERING (PCARS)

Enhanced anti-Stokes Raman scattering has been observed with a 90-degrees scattering geometry when organic liquids including benzene, toluene, and cyclohexane were irradiated by two collinearly superimposed laser beams in a Raman resonance. The effect is analogous to CARS but the phase-matching condition is not fulfilled. It is argued that the CARS phase-matching condition is relaxed by some optical inhomogeneity of the sample medium and that a portion of coherently generated anti-Stokes scattering is directed even at right angles to the incident laser beams. This effect may be called partially coherent anti-Stokes Raman scattering (PCARS).