On the spur lifetime and its temperature dependence in the low linear energy transfer radiolysis of water.
On the spur lifetime and its temperature dependence in the low linear energy transfer radiolysis of water.
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关于水的低线性能量转移辐射分解中的支线寿命及其温度依赖性。
DOI：
10.1039/c2cp42826a
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发表时间：
2012
期刊：
影响因子：
--
通讯作者：
J.-P. Jay-Gerin
中科院分区：
文献类型：
--
作者：
S. Sanguanmith;J. Meesungnoen;Y. Muroya;M. Lin;Y. Katsumura;J.-P. Jay-Gerin
根据辐射化学“杂散模型”的精神，杂散的寿命（τs）是杂散重叠的重要指标，也是低线性能量传递（LET）辐射（如快电子或γ辐照）作用下反应物质分布均匀性的重要指标。事实上，τs给出了在整体溶液中从非均匀刺激动力学到均匀动力学的转变所需的时间，从而定义了所谓的初级（或“逃逸”）自由基和辐射分解的分子产率，这显然是定量理解任何辐照化学系统的基础。在这项工作中，利用一个简单的能量沉积模型，确定了0.4 M脱氧H2SO4水溶液和纯液态水高达350°C的低let辐射分解τs及其温度依赖关系，该模型最初是在杂散中沉积的，然后在轨道膨胀过程中杂散的物种随机扩散，直到杂散重叠完成。与我们以前基于辐照弗里克剂量计模拟的τs计算不同，当前模型不受氧气存在或清除剂使用的任何影响。在酸性溶液中，由此获得的激发寿命值与我们之前的计算非常吻合（然而，在进行适当的修正后，考虑到在Fricke剂量计中氧和Fe2+离子之间竞争H˙原子的可能性，这一效应未包括在我们最初的模拟中）。通过这种方式，我们确认了之前方法的有效性。正如预期的那样，在纯无氧水的情况下，我们计算的达到完全刺激重叠所需的时间基本上与在酸性溶液中发现的时间相同（在不确定度范围内）。这清楚地反映了这样一个事实，即在研究的25-350℃温度范围内，水合电子和H˙原子的扩散系数在中性或酸性介质中分别参与了马刺寿命的总体计算。
In the spirit of the radiation chemical “spur model”, the lifetime of a spur (τs) is an important indicator of overlapping spurs and the establishment of homogeneity in the distribution of reactive species created by the action of low linear energy transfer (LET) radiation (such as fast electrons or γ irradiation). In fact, τs gives the time required for the changeover from nonhomogeneous spur kinetics to homogeneous kinetics in the bulk solution, thus defining the so-called primary (or “escape”) radical and molecular yields of radiolysis, which are obviously basic to the quantitative understanding of any irradiated chemical system. In this work, τs and its temperature dependence have been determined for the low-LET radiolysis of deaerated 0.4 M aqueous solutions of H2SO4 and pure liquid water up to 350 °C using a simple model of energy deposition initially in spurs, followed by random diffusion of the species of the spur during track expansion until spur overlap is complete. Unlike our previous τs calculations, based on irradiated Fricke dosimeter simulations, the current model is free from any effects due to the presence of oxygen or the use of scavengers. In acidic solutions, the spur lifetime values thus obtained are in very good agreement with our previous calculations (after making appropriate corrections, however, to account for the possibility of competition between oxygen and Fe2+ ions for H˙ atoms in the Fricke dosimeter, an effect which was not included in our original simulations). In this way, we confirm the validity of our previous approach. As expected, in the case of pure, oxygen-free water, our calculated times required to reach complete spur overlap are essentially the same (within uncertainty limits) as those found in acidic solutions. This explicitly reflects the fact that the diffusion coefficients for the hydrated electron and the H˙ atom that are involved in the overall calculation of the lifetime of spurs in neutral or acidic media, respectively, are of similar magnitude over the 25–350 °C temperature range studied.
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DOI：
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发表时间：
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期刊：
影响因子：
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DOI：
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发表时间：
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影响因子：
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DOI：
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发表时间：
1991
期刊：
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