PHOTOPHYSICAL PROPERTIES OF C-60(C6H5)(5)CL - A LASER FLASH-PHOTOLYSIS AND PULSE-RADIOLYSIS STUDY

Photophysical and photochemical properties of the singlet and tripler excited states of monochloropentaphenylfullerene [C-60(C6H5)(5)Cl, MCP PF] have been characterized in two different solvents, benzene and ben zonitrile, using two complementary transient absorption techniques, na mely picosecond laser flash photolysis and nanosecond electron pulse r adiolysis. Singlet-singlet and triplet-triplet absorption spectra have been recorded. The quantum yield of triplet formation (phi(T) = 0.45 +/- 0.05) and the intrinsic lifetime of the triplet (tau = 100 +/- 10 mu s) have been determined. Apart from the intrinsic decay of the trip ler to the singlet ground state, another two processes, namely T-T ann ihilation and quenching by the ground state, make important contributi on towards the overal tripler decay rare. Weak charge transfer (CT) co mplexes are formed between MCPPF and the electron-rich amines diphenyl amine (DPA) and triphenylamine (TPA) in benzonitrile solution. On lase r excitation, the CT complex undergoes charge separation, but the radi cal ions undergo very fast geminate recombination to form the tripler state of MCPPF.