On the mechanism of vibrational dephasing in liquid benzene by coherent anti-Stokes Raman scattering using incoherent light

Coherent anti-Stokes Raman scattering using incoherent light (I(2)CARS) for the ring breathing mode of neat benzene is analyzed using a Brownian oscillator lineshaping model. Three low frequency modes of benzene are investigated for their possible role in the vibrational dephasing process. Unlike cw CARS, it is found that I(2)CARS can strongly discriminate between the dephasing activity of the three low frequency modes and suggests that rotation about the C6 axis is responsible for dephasing in this case. This agrees with previous findings in femtosecond CARS experiments on the liquid.