Diffuse-reflectance laser photolysis studies of geminate recombination kinetics of triplet radical pairs adsorbed on microcrystalline cellulose

✍ Scribed by P.P. Levin; L.F. Vieira Ferreira; Silvia M.B. Costa

• Publisher: Elsevier Science
• Year: 1990
• Tongue: English
• Weight: 402 KB
• Volume: 173
• Category: Article
• ISSN: 0009-2614
• DOI: 10.1016/0009-2614(90)85269-i

✦ Synopsis

The geminate recombination kinetics of radical pairs formed by hydrogen-atom transfer from 2,4,6-trimethylphenol to the triplet state of benzophenone coadsorbed on microcrystalline cellulose has been studied, using the diffuse-reflectance laser-flash technique. The kinetics is described by the sum of at least two components, the short one with a characteristic lifetime of about 10 ps, and a long-lived transient with a lifetime of approximately 100 ps. The multiexponential pattern of adsorbed radical-pair decay is ascribed to the appearance of radical pairs in different environments. The application of an external magnetic field has no observable effect on radical-pair decay. The radical pairs adsorbed on cellulose seem to be mainly in a contact-pair state with low molecular mobility of both radicals.