Relaxation of Electronically Excited Hydrogen Peroxide in Liquid Water: Insights from Auger-Electron Emission
Relaxation of Electronically Excited Hydrogen Peroxide in Liquid Water: Insights from Auger-Electron Emission
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液态水中电子激发过氧化氢的弛豫：来自俄歇电子发射的见解
DOI：
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发表时间：
2013
期刊：
影响因子：
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通讯作者：
B. Winter
中科院分区：
文献类型：
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作者：
S. Thürmer;I. Unger;P. Slavíček;B. Winter
用自电离电子能谱研究了过氧化氢水溶液在软X射线辐照下的非辐射弛豫过程。高动能部分的氧1 S H2 O2（aq）俄歇电子能谱揭示双阳离子的最终状态，具有比纯液态水低得多的能量。在量子化学计算的帮助下，有人认为这种低能态来自两个根本不同的弛豫过程。一种是（局部）俄歇衰变，产生H2 O22+（aq）物质，这里的低终态能量来自分子O-O键上的电荷离域。或者，可以形成非局部双阳离子态，对应于包含H2 O2和相邻水分子的电荷分离复合物。不同的电荷分离机制，取决于是否质子动力学的核心水平激发或电离的H2 O2分子参与，进行了讨论。我们还首次提出了部分电子产额X射线吸收谱。
Autoionization electron spectroscopy is applied to study nonradiative relaxation processes of hydrogen peroxide aqueous solution irradiated by soft X-rays. The high kinetic energy part of the oxygen 1s H2O2(aq) Auger-electron spectrum reveals dicationic final states with considerably lower energy than for neat liquid water. Assisted by quantum chemical calculations, it is argued that such lower-energy states arise from two fundamentally different relaxation processes. One is (local) Auger decay, yielding H2O22+(aq) species, and here the low final-state energy arises from charge delocalization across the molecular O–O bond. Alternatively, nonlocal dicationic states can form, corresponding to a charge-separated complex comprising H2O2 and a neighboring water molecule. Different charge-separation mechanisms, depending on whether or not proton dynamics of the core-level excited or ionized H2O2 molecule is involved, are discussed. We also present for the first time the partial electron yield X-ray absorption s...