Vibrational Dephasing of Simple Liquids Investigated by Picosecond and Femtosecond CARS

Using picosecond CARS the dephasing rate of the ν 1 ‐mode of CS 2 is investigated in several solvents and in the neat liquid. A large pressure effect (factor of ≤3) is reported for the range 0 to 4 kbar similar to spontaneous Raman results. For an extended interval of 160 to 450 K, a non‐monotonic temperature dependence is reported for the first time and compared with theoretical models. — A novel non‐degenerate CARS spectrometer is described with 80 fs time resolution and improved measuring accuracy. A dephasing time of T 2 = 608 ± 6 fs is reported for the ν 1 mode of neat acetone of 293 K; negligible inhomogeneous broadening (< 1%) is indicated by the scattering data for this vibration.