水对环己烷-磷酸三丁酯体系γ辐解和脉冲辐解的影响.pdf

物理化学学报( Wuli Huaxue Xuebao)
Acta Phys.-Chim.Sin.,2010,26(7:1909-1914
1909
Article
www.whxb.pku.edu.cn
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
北京大学化学与分子T程学院,北京100871)
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(CHI)-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CH-TBPγ辐解体系中TBP酸式辐解产物的生成,酸式辐解产物的G值从元水体系
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,又通过阻断单重CH2
与TBP之间的能量转移,消除了CHp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(B
为探针的TBP-Bp和CHx~TBP-Bp脉冲辐解体系中,水的加人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CHp2单重态和TBP单重态的产生,但不影响羰自山基的生成.这也许是辐解
体系中大部分(G=1.3)单重态CH2和部分(G=0.8)单重态TBP来源于偕离子对CH2…e]和[TBP+…e门]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提剂
关键词;环己烷;单重态;偕离子对;辐解;磷酸三丁酯;水
中图分类号:O644
Effect of Water on y-radiolysis and Pulse Radiolysis of Cyclohexane
Tributylphosphate System
DU YI-KUI*WU Ji-lan
College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, P. R. China
Abstract To determine the origin of the radiolytic product singlet state of hydrocarbons, the effect of water on the
radiolysis and pulse radiolysis of cyclohexane(Cm 2)tributylphosphate( BP) solution was studied. In the y-radiolysis
of C HT BP 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
TBP itself, but also the energy transfer from the singlet CEH,2 to TBP In the pulse radiolysis of Tbp-benzophenone
(Bp)solution and COHIRTBP-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
[C e and [TBP.e ] giving ketyl radicals but depressing the formation of singlet COH and singlet TBP. This
might be direct evidence that most(G=1.3)of the singlet Cohpz and part(G=0.8) of the singlet TBP come from the
recombination of geminate ions H.e and (TBP*e ] respectively Due to its high polarity, water could be
used as a specific scavenger of the geminate ions that can form excited states wia fast geminate recombination
Key Words: Cyclohexane; Singlet: Geminate ions; Radiolysis; Tributylphosphate; Water
By virtue of low dielectric constant and having only C-C uid hydrocarbons are subjected to ionizing radiation, cxcited stat
and C-H bonds. hydrocarbons represent an ideal medium to
In be formed instantly by direct excitation and almost instantly
study the radiation chemistry in non-polar media -. When li
(in ca 100 ps)by geminate ions recombination. The origin of the
Received: December 21, 2009; Revised: March 2, 2010; Published on Web: May 25, 2010
Correspondingauthors.Email:ydu@iccas,ac.n,wangwqchem(@pku.edu.cn;Tel:+86-10-62635054Fax:+86-10-62563167
The project was supported by the Nuclear Industrial Science Foundation of China(H7196NY002
国家核科学基金(H7196NY02)资助项日
C Editorial office of Acta Physico-chimica Sinica