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 C-6 axis is responsible for dephasing in this case. This agrees with previous findings in femtosecond CARS experiments on the liquid. (C) 1998 Elsevier Science B.V. All rights reserved.