Saturated coherent Raman scattering spectroscopy for molecular gases

This paper discusses saturation of a Raman-scattering transition by biharmonic pumping waves, with probing by coherent anti-Stokes Raman scattering ASRS. It is shown that oscillations in the population difference on this transition at the difference frequency between the pumping and probe waves causes the shape of the homogeneous line for the ASRS signal to contain a characteristic feature: a dip with width determined by the time $T_1$. The results are extended to the case of a Doppler-broadened line. There is a discussion of the scope for coherence spectroscopy free from Doppler broadening.