Polarization-selective femtosecond Raman spectroscopy of isotropic and anisotropic vibrational dynamics in liquids

Femtosecond nonresonant pump–probe experiments using variable polarization configurations are used to directly measure the isotropic and anisotropic polarizability dynamics of the intramolecular vibrational modes of liquid CCl4. These two measurements form a fundamental `basis setʹ that describes the nuclear nonresonant Raman dynamics of an isotropic sample. The isotropic spectrum observes only those dynamics that are totally symmetric, such as the A1 C–Cl stretch, whereas the anisotropic response only observes the dynamics of the depolarized modes of E and T2 symmetry.