Abstract
Laser flash photolysis of an alternating copolymer of phenyl isopropenyl ketone with styrene was studied (25ns laser flash of 347nm light). Transient absorption spectrum obtained immediately after the end of the flash was due to a triplet-triplet absorption of benzoyl chromophore. Since a fraction of the triplet state was decayed by the triplet-triplet annihilation, a triplet decay rate constant was determined to be 8.7×106s-1 from the extrapolation of the absorbed photons at zero. Quantum yields of the triplet formation and the α-cleavage reaction are estimated to be 0.6 and 0.3, respectively. Quenching rate constants by naphtalene and oxygen are (9±1)×108l/mol. s. These bimolecular rate constants with the T-T annihilation are larger (1.5 to 3 times) than those of homopolymer and random copolymers.
