Temporally two-dimensional fifth-order Raman scattering on intermolecular vibrations in CS2/pentane binary mixtures

Third- and fifth-order impulsive stimulated Raman scattering experiments ar e performed to study low-frequency intermolecular vibrations in CS2/pentane binary mixtures. The changes of the optical Kerr effect response cannot be assigned unequivocally to a single microscopic process. In particular, the homogeneous and inhomogeneous line broadening mechanisms cannot be determi ned. Temporally two-dimensional Raman scattering experiments indicate that the correlation time of fluctuations of the intermolecular potential decrea ses upon dilution. The experimental results give evidence of strong couplin g between the ultrafast coherent vibrations and the slow reorientational di ffusion.