Partially coherent anti-Stokes Raman scattering (PCARS): A comparative band-shape analysis of the spontaneous Raman and PCARS spectra of toluene

Abstract

Partially coherent anti‐Stokes Raman scattering (PCARS) spectrum of liquid toluene has been measured. The observed shape of the 1004 cm⁻¹ band is asymmetric unlike that of the spontaneous Raman spectrum. A least‐squares fitting shows that this asymmetric PCARS band‐shape is fitted well to ‖χ⁽³⁾‖² but not to the imaginary part of χ⁽³⁾. The origin of the observed band asymmetry is the nonresonant term of χ⁽³⁾, which is real and does not affect the spontaneous Raman band shapes. These results support our previous interpretation that the PCARS intensity originates from the relaxation of the CARS phase matching condition due to the optical inhomogeneity of the sample.