Control of X-ray Induced Electron and Nuclear Dynamics in Ammonia and Glycine Aqueous Solution via Hydrogen Bonding.
Control of X-ray Induced Electron and Nuclear Dynamics in Ammonia and Glycine Aqueous Solution via Hydrogen Bonding.
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通过氢键控制氨和甘氨酸水溶液中的 X 射线诱导电子和核动力学。
DOI：
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发表时间：
2015
影响因子：
3.3
通讯作者：
B. Winter
中科院分区：
文献类型：
--
作者：
I. Unger;D. Hollas;R. Seidel;S. Thürmer;E. F. Aziz;P. Slavíček;B. Winter
最近，在水相中发现了一系列新的自电离过程。该过程由溶质分子的核心电子电离引发，并涉及沿溶质-溶剂氢键的质子转移。结果，形成了短寿命的单电荷阳离子，其结构在溶质和溶剂分子之间共享质子。这些分子瞬态通过自电离而衰减，从而产生活性双离子物质，其正电荷在整个分子实体上离域。在这里，我们研究了水合氨和甘氨酸核心电离后的超快电子和核动力学。这两种分子都可以作为模型来探索非局部弛豫过程在蛋白质表面和水溶液之间界面的化学反应中可能发挥的作用。真空中液体微射流的高精度俄歇电子能谱测量揭示了位置电离动力学过程的本质。质子转移介导的过程是通过俄歇光谱高能尾部的电子信号来识别的，而相应气相分子的俄歇光谱中没有类似物。对于氘代分子来说，这种高能尾部受到抑制。发现与氢键较强的水合H 2 O分子相比，氨水的这种同位素效应更小。甘氨酸中水合氨基的氢键更弱，导致质子转移可忽略不计。使用量子化学和分子动力学方法解释了氮 1 核级电离形成的动力学过程和物质。在此类计算的帮助下，我们讨论了质子转移介导的弛豫过程发生的条件。我们还认为溶剂解放动力学是另一种分子间超快弛豫途径。此外，我们还为核心电离时氨水中的伞型运动提供了实验证据。该分子内通道与溶液中的分子间弛豫过程并行进行。
Recently, a new family of autoionization processes has been identified in aqueous phases. The processes are initiated by core-electron ionization of a solute molecule and involve proton transfer along the solute-solvent hydrogen bond. As a result, short-lived singly charged cations form with structures sharing a proton between solute and solvent molecules. These molecular transients decay by autoionization, which creates reactive dicationic species with the positive charges delocalized over the entire molecular entity. Here, we investigate the ultrafast electron and nuclear dynamics following the core ionization of hydrated ammonia and glycine. Both molecules serve as models for exploring the possible role of the nonlocal relaxation processes in the chemical reactivity at the interface between, for instance, a protein surface and aqueous solution. The nature of the postionization dynamical processes is revealed by high-accuracy Auger-electron spectroscopy measurements on liquid microjets in vacuum. The proton-transfer-mediated processes are identified by electron signals in the high-energy tail of the Auger spectra with no analogue in the Auger spectra of the corresponding gas-phase molecule. This high-energy tail is suppressed for deuterated molecules. Such an isotope effect is found to be smaller for aqueous ammonia as compared to the hydrated H2O molecule, wherein hydrogen bonds are strong. An even weaker hydrogen bonding for the hydrated amino groups in glycine results in a negligibly small proton transfer. The dynamical processes and species formed upon the nitrogen-1s core-level ionization are interpreted using methods of quantum chemistry and molecular dynamics. With the assistance of such calculations, we discuss the conditions for the proton-transfer-mediated relaxation processes to occur. We also consider the solvent librational dynamics as an alternative intermolecular ultrafast relaxation pathway. In addition, we provide experimental evidence for the umbrella-type motion in aqueous ammonia upon core ionization. This intramolecular channel proceeds in parallel with intermolecular relaxation processes in the solution.
质子转移介导的 X 射线照射液态水中非局域电子弛豫过程的增强
影响因子：
15
作者：
Slavíček P;Winter B;Cederbaum L.S;Kryzhevoi N.V.
通讯作者：
Kryzhevoi N.V.