HYDROGEN ABSTRACTION DYNAMICS IN SOLUTION STUDIED BY PICOSECOND INFRARED-SPECTROSCOPY

Solution-phase bimolecular reactions are observed directly for the first time using transient infrared absorption spectroscopy. Laser photolysis of Cl2 using a UV pulse at 355 nm creates chlorine radicals in neat cyclohexane solution and initiates a hydrogen abstraction reaction to form HCI or DCl (in deuterated solvent) as products. Picosecond infrared pulses at 3.3 or 5 mum probe the vibrational state populations to determine the time development of the product formation. The observed reaction rate of HCl formation is (5.6 +/- 1) X 10(9) M-1 s-1, which is approximately 14 +/- 6 times slower than previously reported gas-phase kinetic results.