物理化学学报 >> 2010, Vol. 26 >> Issue (07): 1909-1914.doi: 10.3866/PKU.WHXB20100720

光化学与光谱 上一篇    下一篇

水对环己烷-磷酸三丁酯体系γ辐解和脉冲辐解的影响

杜宜奎, 吴季兰   

  1. 北京大学化学与分子工程学院, 北京 100871
  • 收稿日期:2009-12-21 修回日期:2010-03-02 发布日期:2010-07-02
  • 通讯作者: 杜宜奎, 吴季兰 E-mail:ydu@iccas.ac.cn; wangwqchem@pku.edu.cn

Effect of Water on γ-Radiolysis and Pulse Radiolysis of Cyclohexane-Tributylphosphate System

DU Yi-Kui, WU Ji-Lan   

  1. College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, P. R. China
  • Received:2009-12-21 Revised:2010-03-02 Published:2010-07-02
  • Contact: DU Yi-Kui, WU Ji-Lan E-mail:ydu@iccas.ac.cn; wangwqchem@pku.edu.cn

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摘要：

为确定辐解体系中烷烃单重态的来源, 研究了水对环己烷(C6H12)-磷酸三丁酯(TBP)体系γ辐解和脉冲辐解的影响. 水显著地抑制C6H12-TBP γ辐解体系中TBP酸式辐解产物的生成, 酸式辐解产物的G值从无水体系的8.2降至水饱和体系的1.9, 表明水分子既抑制了TBP自身辐解生成的TBP单重态, 又通过阻断单重态C6H12与TBP之间的能量转移, 消除了C6H12自身辐解对单重态TBP的酸式辐解产物的敏化作用. 但在以二苯酮(Bp)为探针的TBP-Bp和C6H12-TBP-Bp脉冲辐解体系中, 水的加入并未抑制辐解产物羰自由基的产额, 其机理是, 水分子通过与偕离子对反应而抑制C6H12单重态和TBP单重态的产生, 但不影响羰自由基的生成. 这也许是辐解体系中大部分(G=1.3)单重态C6H12和部分(G=0.8)单重态TBP来源于偕离子对[C6H12·+…e-]和[TBP·+…e-]的复合的直接证据. 由于极性较大, 水可用作偕离子对的高效捕捉剂.

关键词: 环己烷, 单重态, 偕离子对, 辐解, 磷酸三丁酯, 水

Abstract:

To determine the origin of the radiolytic product singlet state of hydrocarbons, the effect of water on the γ-radiolysis and pulse radiolysis of cyclohexane (C6H12)-tributylphosphate (TBP) solution was studied. In the γ-radiolysis of C6H12-TBP solutions, the addition of water can remarkably lower the yield of the acid product of TBP. The G value of the acid product dropped from 8.2 in the system containing no water to about 1.9 in the system saturated with water. This suggests that water inhibits not only the output of singlet TBP directly induced by the radiation energy absorbed by TBP itself, but also the energy transfer from the singlet C6H12 to TBP. In the pulse radiolysis of TBP-benzophenone (Bp) solution and C6H12-TBP-Bp solutions with Bp as a probe, the added water did not depress the yield of the radiolytic intermediate ketyl radicals. This phenomenon can be interpreted as that water reacted with the geminate ions [C6H12·+…e-] and [TBP·+…e-], giving ketyl radicals but depressing the formation of singlet C6H12 and singlet TBP. This might be direct evidence that most (G=1.3) of the singlet C6H12 and part (G=0.8) of the singlet TBP come from the recombination of geminate ions [C6H12·+…e-] and [TBP·+…e-], respectively. Due to its high polarity, water could be used as a specific scavenger of the geminate ions that can formexcited states via fast geminate recombination.

Key words: Cyclohexane, Singlet, Geminate ions, Radiolysis, Tributylphosphate, Water