A pulse radiolysis study on energy transfer mechanism in trioctylphosphineoxide-cyclohexane and tributylphosphate-cyclohexane systems by using benzophenone as a probe

Measuring the G values of ketyl radicals, benzophenone has been used as a p robe to study the energy transfer mechanism in trioctylphosphineoxide(TOPO) -cyclohexane and tributylphosphate(TBP) CH systems under pulse radiolysis. Results showed that there was a process of energy transfer between the exci ted CH and TBP or TOPO, which coincided with our previous experiments on fi nal product analysis. Rate constants (k) of energy transfer and G(CH*) (G v alue of singlet cyclohexane), which are k = 4.8 x 10(9) dm(3) mol(-1) . S-1 , G(CH*) = 1.3 x 0.1 for TBP and k = 8.3 x 10(12) dm(3) mol(-1) s(-)1, G(CH *) = 1.4 +/- 0.1 for TOPO, were obtained by Stern-Volmer method. The abnorm ality of the rate constant for TOPO is discussed. Another process fitted wi th WAS equation was assumed to be geminate ions scavenging, and the alpha = 7.3, G(gi) = 3.8 +/- 0.1 for TBP, alpha = 649, G(gi) = 3.7 +/- 0.1 for TOP O, were gained. Meanwhile the mechanism of the latter process were also dis cussed. (C) 1999 Elsevier Science Ltd. All rights reserved.