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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Spur reactions observed by picosecond pulse radiolysis in highly concentrated bromide aqueous solutions
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Spur reactions observed by picosecond pulse radiolysis in highly concentrated bromide aqueous solutions

机译：在高浓度溴化物水溶液中通过皮秒脉冲辐射分解观察到的杂色反应

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摘要

The formation of the well-known product Br_3 ~-, observed in the steady-state radiolysis of highly concentrated Br-aqueous solutions, has now been directly observed at ultrashort times corresponding to the relaxation of the spur. The transient absorption induced by picosecond pulse radiolysis of 6 M Br-aqueous solution was probed simultaneously at 260 nm with the third harmonic laser wave and from 350 to 750 nm with a supercontinuum generated by the fundamental laser wave. This approach allows several transient radiolytic species to be followed in parallel, particularly the solvated electron, BrOH~(-?), Br_2 ~(-?), and Br_3 ~-. The kinetics measured within 4 ns at 260 and 370 nm clearly exhibit that the decay of Br_2 ~(?-)is correlated with the formation of Br_3 ~-. In highly concentrated Br-solutions, the OH ?radical is fully replaced by Br_2 ~(?-), and the spur kinetics of OH?radical in pure water is comparable with that of Br_2 ~(-?). Model calculations indicate that the main OH?radical combination product H_2O _2in pure water has formation kinetics similar to that of Br _3 ~-in 6 M Br-solutions. Moreover, they point out that oxidation of Br-occurs within the electron pulse both by direct energy absorption and by scavenging of the water radical cation, H _2O~(?+).
机译：在高浓度Br水溶液的稳态辐射分解中观察到的众所周知的产物Br_3〜-的形成，现在已经在对应于杂散松弛的超短时间内直接观察到了。皮秒脉冲辐射分解6 M Br水溶液引起的瞬态吸收在三次谐波激光的同时在260 nm探测，在基波产生的超连续谱在350 nm到750 nm探测。这种方法允许并行跟踪几种瞬态辐射分解物质，特别是溶剂化的电子BrOH〜（-？），Br_2〜（-？）和Br_3〜-。在260 nm和370 nm的4 ns内测量的动力学清楚地表明，Br_2〜（？-）的衰减与Br_3〜-的形成有关。在高浓度的Br溶液中，OH自由基被Br_2〜（？-）完全取代，并且OH自由基在纯水中的刺激动力学与Br_2〜（-？）相当。模型计算表明，纯净水中的主要OH自由基组合产物H_2O_2的形成动力学与6M Br溶液中的Br_3〜-相似。此外，他们指出，Br的氧化在电子脉冲内通过直接能量吸收和通过清除水自由基阳离子H _2O〜（α+）发生。

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