Numerical modeling of partially coherent anti-Stokes Raman scattering (pCARS) in transparent molecular liquids

• Key characteristics of partially coherent anti-Stokes Raman scattering (pCARS) in molecular liquids are numerically modeled. • pCARS experimental findings in liquid toluene, benzene and benzene solutions in organic liquids were numerically simulated. • The physical nature of pCARS elucidated: seeded third-order Raman scattering effect – complex stimulated-parametric process. • The mechanism for realization of pCARS is presented alternatively to the molecular physics fluctuation theoretical treatment. • The proposed simple model and the physical interpretation of pCARS can be applied in studies of colloid molecular systems. In this study, the key characteristics of the so called partially coherent anti-Stokes Raman scattering (pCARS) are numerically modeled in order to explain the physical nature of this nonlinear Raman effect. The experimental data obtained by Ishibashi and Hamaguchi, the pioneer researchers of pCARS, are simulated by use of analytical description different from their original physical interpretation. The numerical results for the spatial distribution of the anti-Stokes Raman signal in pCARS, the shape of the pCARS spectral line, and the dependence of the pCARS signal intensity on the laser pulse intensity, as well as on the concentration and temperature of the Raman medium, all matching the pCARS experimental data, indicate a complex parametric-stimulated mechanism of generation/amplification of pCARS. The differences of pCARS from ordinary CARS (fully coherent process of Raman scattering) are highlighted.