Scavenging the Water Cation in Concentrated Acidic Solutions
Scavenging the Water Cation in Concentrated Acidic Solutions
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DOI：
10.1021/acs.jpca.5b07601
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发表时间：
2015-10-29
影响因子：
2.9
通讯作者：
Mostafavi, Mehran
中科院分区：
文献类型：
--
作者：
Ma, Jun;LaVerne, Jay A.;Mostafavi, Mehran
利用皮秒脉冲辐解技术研究了高浓度和强酸性溶液中SO 42-、PO 43-、Cl-和Br-的快速氧化过程中形成的SO 4中心点-、H2 PO 4、Cl-2（中心点-）和Br-2（中心点-）物种的动力学。将实验结果与模型预测进行比较，以深入了解在快速时间尺度上发生的可能机制。简单的动力学涉及的氧化OH中心点自由基形成的辐解水分解不能解释所观察到的产量在很短的时间内（在电子脉冲类似于7 ps）。由入射电子引起的马刺反应的扩散动力学模拟表明，额外的氧化的溶质必须在很短的时间内发生，并涉及它们的直接电离沿着清除的高氧化性H2O中心点+自由基形成的初始电离的水介质。对于PO_4 ~（3-）、SO_4 ~（2-）、Cl ~-和Br ~-溶液，清除的H_2O中心点+自由基的分数分别为0.26、0.68、0.92和0.97。这些研究代表了第一个半定量估计的H2O中心点+自由基清除馏分这样一个广泛的溶质。
Picosecond pulse radiolysis techniques were used to observe the kinetics of the SO4 center dot-, H2PO4, Cl-2(center dot-), and Br-2(center dot-) species formed in the fast oxidation of concentrated and highly acidic solutions of SO42-, PO43-, Cl-, and Br-. Experimental results were compared with model predictions to gain insight into the possible mechanisms occurring on the fast time scales. Simple kinetics involving the oxidizing OH center dot radical formed by radiolytic water decomposition could not account for the observed yields at the very short times (within the electron pulse similar to 7 ps). Diffusion-kinetic simulations of the spur reactions induced by the incident electrons show that additional oxidation of the solutes must occur at very short times and involves their direct ionization along with scavenging of the highly oxidizing H2O center dot+ radical formed in the initial ionization of the water medium. The fraction of H2O center dot+ radicals scavenged varies as 0.26, 0.68, 0.92, and 0.97 for PO43-, SO42-, Cl-, and Br- solutions, respectively. These studies represent the first semiquantitative estimation of the H2O center dot+ radicals scavenging fractions for such a wide range of solutes.