Frequency shifts in stimulated Raman scattering

The nonresonant contributions to the nonlinear susceptibility χ(3)
produce a frequency chirp during stimulated Raman scattering. In
the case of transient stimulated Raman scattering, the spectrum of
the generated Stokes pulse is found at higher frequencies than
expected from spontaneous Raman data. The frequency difference can
be calculated from the theory of stimulated Raman scattering.