PHOTOCHEMICAL PROPERTIES OF C-60 - TRIPLET-EXCITED C-60 QUENCHING BY ELECTRON-ACCEPTORS TCNQ AND TCNE IN SOLUTION - LASER PHOTOLYSIS STUDY

The quenching of triplet-excited C-3(60) by electron acceptors TCNQ and TCNE has been established in nonpolar toluene and moderately polar benzonitrile solutions. The quenching constants k(q) are 5.5 x 10(9) in toluene, 2.2 x 10(9) in benzonitrile for TCNQ and 7.9 x 10(5) in toluene, 4.2 x 10(8) (M s)-1 in benzonitrile for TCNE. The C-3(60) quenching can be explained by triplet exciplex formation. The time-resolved spectra of the C60/TCNE system exhibit a well pronounced charge-transfer ''cited state [C60delta+)...TCNE(delta-] in benzonitrile.