Ultrafast bimolecular radical reaction proceeds between photoexcited p-terphenyl and carbon tetrachloride. The lifetime of the first excited singlet (Si) state of p-terphenyl in carbon tetrachloride measured with picosecond time-resolved fluorescence spectroscopy is 5.6 ps, shorter than the typical lifetime in ordinary solvents, 0.95-2.8 ns, by a factor of 170 or more. Time-resolved infrared spectroscopy reveals the generation of the trichloromethyl (CCl(3)) radical as a reaction intermediate. The decay kinetics of the CCl(3) radical indicates that the CCl(3) radical and the p-terphenyl-Cl radical adduct, both of which are produced simultaneously by a radical reaction between S(1) p-terphenyl and carbon tetrachloride, recombine to form the product. The picosecond time-resolved Raman spectrum of the reactant S(1) p-terphenyl shows that the dephasing process for the four vibrational modes at 1640, 1497, 1180, and 1017 cm(-1) is selectively accelerated in carbon tetrachloride. The four vibrational modes probably have a large contribution from the motion of a specific atom or atoms where the intermolecular interaction that induces the bimolecular reaction is present. Copyright (C) 2008 John Wiley & Sons, Ltd.