Geminate recombination kinetics of triplet radical ion pairs on silica studied by diffuse reflectance laser flash photolysis

✍ Scribed by Peter P. Levin; L.F. Vieira Ferreira; Silvia M.B. Costa; I.V. Katalnikov

• Publisher: Elsevier Science
• Year: 1992
• Tongue: English
• Weight: 761 KB
• Volume: 193
• Category: Article
• ISSN: 0009-2614
• DOI: 10.1016/0009-2614(92)85832-u

✦ Synopsis

Geminate recombination kinetics has been studied using the diffuse reflectance laser flash technique of radical ion pairs (RIP) formed by electron transfer from triphenylamine to triplet benzophenone, 9,1 O-anthraquinone, duroquinone or 2,6diphenyl-1,4benzoquinone both adsorbed onto porous silica. The kinetics can be described by two formalisms: a first-order law with Gaussian distribution on the free energy which gives an average rate constant /c= IO6 s-' and a small width of distribution; or by a fractallike analysis which supports the contribution of a fast motion in the radical ion pair recombination and the heterogeneity of the media. A retardation of RIP geminate recombination up to 25% under an external magnetic field shows evidence of some contribution of the magnetosensitive mechanisms of the RIP spin evolution.