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

Abstract

Efficient intermolecular energy transfer between the C–Br stretching modes ν2 and ν5 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.