PHOTOCHEMISTRY OF DIPHENYLKETYL RADICALS IN POLAR-SOLVENTS

The photolysis of diphenylketyl radicals in acetonitrile leads to their photobleaching with a quantum yield of 0.10. The decay of the excited radicals occurs by four different pathways: (a) doublet–doublet fluorescence; (b) radiationless decay; (c) electron photoejection, which accounts for 20% of the observed bleaching; and (d) O–H bond cleavage leading to benzophenone, which is presumed to account for the remaining 80% of the bleaching. The electrons produced in acetonitrile are trapped by ground-state benzophenone to yield its radical anion (λmax 710 nm); addition of electron scavengers (N2O or acetone) prevents the formation of Ph2CO·-. © 1990, American Chemical Society. All rights reserved.