Temporally two‐dimensional Raman spectroscopy of liquids by six‐wave mixing with ultra‐short pulses

Abstract

Abstract A temporally two‐dimensional Raman spectroscopic method was developed to observe the fifth‐order optical response of liquids. Taking advantage of temporal two‐dimensionality, this technique can unambiguously distinguish homogeneous and inhomogeneous contributions to the dephasing of low‐wavenumber vibrational modes. The measurement of the fifth‐order optical response of liquid CS 2 was conducted by ultra‐fast non‐resonant six‐wave mixing using five different pulses. 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 ps −1 .