Time-resolved observation of intermolecular vibrational energy transfer in liquid bromoform

Efficient intermolecular energy transfer between the C-Br stretching modes nu(2) and nu(5) of bromoform molecules in the liquid phase has been observed directly in time-resolved experiments applying vibrational pump-probe spectroscopy with picosecond laser pulses. An analysis of results on CHBr3, CDBr3, and an isotopic mixture of both yields a typical time constant of 25 +/- 15 ps for this rather efficient, near-resonant intermolecular relaxation channel. Additional new details about the intramolecular pathways of vibrational energy relaxation have been determined for the pure substances. (C) 2000 American Institute of Physics. [S0021-9606(00)51214-8].