Filamentation-assisted time-resolved Raman spectroscopy in molecular gases

Raman excitation of molecular gases can be accomplished and detected by optical filamentation of ultrashort laser pulses in the investigated sample. Exploiting this technique, we could clearly resolve the full Raman response of H2 as well as the major vibrational modes in several molecules (N2, O2, CO2, N2O, CH4, C2H6). The experimental results show that the temporal requirements for efficient time-resolved Raman spectroscopy, namely pump and probe pulses shorter than the investigated dynamics, can be relaxed by the occurrence of self-compression during pulse filamentation and by the exploitation of spectrally-resolved detection.