“…Although the multi-mode Brownian oscillator model (Tanimura & Mukamel, 1993;Nagata & Tanimura, 2006) is also commonly used to characterize the low-frequency spectra (Giraud et al, 2003;, the former analytical model is used throughout this chapter. Most of the earlier femtosecond RIKES studies were conducted to clarify the intermolecular vibrational and orientational dynamics in pure molecular liquids and binary mixtures (Kinoshita et al, 1996;Castner & Maroncelli, 1998;Smith & Meech, 2002;Zhong & Fourkas, 2008;. Nowadays, femtosecond RIKES is also used to study the intermolecular vibrational dynamics, reorientation, and microscopic intermolecular interactions of complex condensed phases (Hunt et al, 2007;Farrer & Fourkas, 2003) such as polymer liquids and solutions, microemulsions, aqueous protein films and solutions, and solvents in nanoporous glasses.…”