- 作者: 林定平; 范國維; 葉錫溶; 陳美穗
- 作者服務機構: Department of Chemistry, National Tsing Hua University
- 中文摘要: The intrinsic characteristics of radical pairs produced in squalane and in cetane receiving high gamma-dose are extensively studied with the EPR technique at temperatures from 77°K up to 150°K. The spectra of the paired radicals occur at g=4 with a very low transition probability in contrast to that of isolated radicals which appear at g=2. A well-resolved hyperfine spectrum corresponding to the species (CH3CH2..CH2CH3) is observed in cetane. The isothermal decay rates of radical pairs in cetane below 100°K are significantly slow; however, the decay kinetics at 150°K is first order with rate constant=1.86 min¯1. A relatively slower decay rate is obtained for isolated radicals suggesting that the decay mechanism of paired radicals is through geminate recombination. The relative inter-radical distance in radical pairs is known from a decay curve as a function of temperature. The yields of radical pairs are low in both matrices, only few percents of those of isolated radicals. The formation mechanisms of paired radicals with direct radiolytic bond scission process are discussed in connection with the experimental observations.
- 英文摘要: --
- 中文關鍵字: --
- 英文關鍵字: --