Fifth Order Optical Response of Liquid CS2Observed by Ultrafast Nonresonant Six-Wave Mixing

The first observation of the fifth order optical response of liquid C${\mathrm{S}}_2$ was conducted by ultrafast nonresonant six-wave mixing with five different pulses. The technique allows us to unambiguously distinguish homogeneous and inhomogeneous contributions to spectral broadening of low frequency vibrational modes. The experimental results are reproduced well in terms of one overdamped mode in the homogeneous limit and one underdamped mode with the width of the inhomogeneity less than $2.5{\mathrm{ps}}^{-1\mathrm{}}$.