Photochemical bimolecular reaction between biphenyl and carbon tetrachloride: observed ultrafast kinetics and diffusion-controlled reaction model

Ultrafast bimolecular reaction kinetics between photoexcited biphenyl and c arbon tetrachloride, observed by femtosecond time-resolved fluorescence spe ctroscopy, is successfully interpreted by theories of diffusion-controlled reactions. The obtained decay kinetics is well explained by Smoluchowski's theory of diffusion-controlled reactions when the parameter R, distance bet ween the reactants, is 0.39 nm. A modified kinetic theory by Collins and Ki mball also explains the results satisfactorily, when R is 0.40 nm and the b imolecular reaction rate constant k(act) is 3.4 x 10(11) dm(3) mol(-1) s(-1 ). It is suggested that molecular motions in solution for a time period of a few picoseconds is described by diffusion. (C) 2001 Elsevier Science B.V. All rights reserved.