New investigations of polyatomic molecules in the liquid state using picosecond light pulses

A description is given of a new method for investigating vibrational excitations of molecules in liquids: this method involves a preliminary brief excitation of a molecule by two picosecond pulses, differing in frequency by an amount which is in resonance with natural vibrations of the molecule, followed by a subsequent prolonged investigation of free relaxation of the excited system. The results are reported of an investigation of this kind made on C₆H₁₂ in the range 2875–2925 cm^–1. Lines not resolved in the usual spontaneous Raman spectrum were observed. The position of the well-known 2923 cm^–1 line was determined more accurately.