Horne Gregory P, Pimblott Simon M, LaVerne Jay A
California State University at Long Beach , Long Beach, California 90804, United States.
Radiation Laboratory, University of Notre Dame , Notre Dame, Indiana 46556, United States.
J Phys Chem B. 2017 Jun 1;121(21):5385-5390. doi: 10.1021/acs.jpcb.7b02775. Epub 2017 May 23.
Comparison of experimental measurements of the yield of molecular hydrogen produced in the gamma radiolysis of water and aqueous nitrate solutions with predictions of a Monte Carlo track chemistry model shows that the nitrate anion scavenging of the hydrated electron, its precursor, and hydrogen atom cannot account for the observed decrease in the yield at high nitrate anion concentrations. Inclusion of the quenching of excited states of water (formed by either direct excitation or reaction of the water radical cation with the precursor to the hydrated electron) by the nitrate anion into the reaction scheme provides excellent agreement between the stochastic calculations and experiment demonstrating the existence of this short-lived species and its importance in water radiolysis. Energy transfer from the excited states of water to the nitrate anion producing an excited state provides an additional pathway for the production of nitrogen containing products not accounted for in traditional radiation chemistry scenarios. Such reactions are of central importance in predicting the behavior of liquors common in the reprocessing of spent nuclear fuel and the storage of highly radioactive liquid waste prior to vitrification.
将水和硝酸盐水溶液的γ辐射分解中产生的分子氢产率的实验测量结果与蒙特卡罗径迹化学模型的预测结果进行比较，结果表明，硝酸根阴离子对水合电子、其前体和氢原子的 scavenging 作用无法解释在高硝酸根阴离子浓度下观察到的产率下降。将硝酸根阴离子对水的激发态（由水自由基阳离子的直接激发或与水合电子前体的反应形成）的猝灭纳入反应方案，使得随机计算结果与实验结果高度吻合，证明了这种短寿命物种的存在及其在水辐射分解中的重要性。从水的激发态到硝酸根阴离子的能量转移产生一个激发态，为传统辐射化学场景中未考虑的含氮产物的产生提供了一条额外途径。此类反应对于预测乏核燃料后处理中常见的液体以及玻璃固化前高放射性液体废物储存中的行为至关重要。
