Proton Transfer Dynamics in Water and Effect of Water Fluctuation on Chemical Reactions

水中质子传递动力学及水波动对化学反应的影响

• 批准号: 08404040
• 负责人: OHMINE Iwao
• 金额: $ 24.26万
• 依托单位: Nagoya University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (A)
• 财政年份: 1996
• 资助国家: 日本
• 起止时间: 1996 至 1998
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08404040/
• 关键词: Water; Proton Transfer; Chemical Reaction; Hydrogen Bond; Fluctuation; Freezing; Nonlinear Spectroscopy; Simulation; 水; 氷; 大域的ポテンシャルエネルギー面; 集団運動; 揺らぎ; 超高速高次非線型分光; 電荷移動反応; クラスター; 化学反応ダイナミックス; 統計理論; ポテンシャルエネルギー面

Various aspects of Water Dynamics were analyzed ; (1) Fluctuation and Relaxation in Liquid Water and their Observation, (2) Proton Transfer in Liquid Water and Ice, (3) Solvation Dynamics in Supercritical Water, and (4) Mechanism of Water Freezing.(1) Water has the rugged potential energy surface involving various deep energy minima with different hydrogen bond network structures. Water undergoes the sluggish dynamics on this potential energy surface. In a short time scale liquid water is thus amorphous gel-like, while in a very longer time scale it exhibits diffusional motion as an ordinal liquid. In between these time scales, the hydrogen bond network rearrangement occurs intermittently and locally in space, involving the local collective motions of tens of water molecules accompanied with the large energy fluctuation. The various experimental techniques to observe the effects of intermittent collective motions in water are discussed. Particular emphasis is on the higher-order nonlin … More ear specutroscopies since these methods deal with the phase-space dynamics of a system. There have been intensive theoretical investigations proposing to apply the echo-type experiment, i.e. the off-resonant fifth order (two-dimensional (2D) Raman) spectroscopy to distinguish the homogeneous and the inhomogeneous elements in liquid dynamics.(2) Proton transfer in water is assisted by Hydrogen Bond Network Rearrangement (HBNR), making some water molecules three-coordinated. Proton transfer takes place on these three-coordinated water molecules. On the other hand, the protonated water molecule is four-coordinated in ice, but its interaction with the fourth coordinated water molecule is repulsive (while those with first three are attractive) ; four-coordinated geometrically and three-coordinated energetically. Due to this repulsive interaction with the fourth water molecule, 0-- (H) --O distances with the other three water molecules become short and thus facile proton transfer can take place even in ice without causing a significant HBNR.^2(3) We also analyze the mechanism of the water molecule dissociation. A water molecule dissociates to H^+ and OH (ionic channel) in liquid water. In the gas phase, however, water is known to separate into two radicals, H and OH.This radical channel is about 290 kcal/mol more stable than the ionic channel. In water the ion channel is extensively stabilized by hydration and thus water yields pH = 7. It is also found that in super-critical water the hydration is stronger than in water in spite of the fact that water molecular density is smaller, and hence the ionic channel becomes even more stable.(4) We have investigated the freezing mechanism of liquid water was investigated by using molecular dynamics simulation. Placing a small ice-structured unit in a center of a simulation box, the processes of forming an well-ordered hydrogen bond network around it were monitored. It was found that crystallization suddenly takes place after certain induction-time. Various analyses were made to find how the hydrogen bond network grows in this freezing mechanism. Less

分析了水动力学的各个方面：（1）液态水的波动和弛豫及其观测，（2）液态水和冰中的质子转移，（3）超临界水中的溶剂化动力学，以及（4）水冻结的机理。(1)水具有凹凸不平的势能面，包含着各种不同氢键网络结构的深层能量极小值。水在这个势能面上经历缓慢的动力学过程。因此，在短时间尺度下，液态水是无定形凝胶状的，而在非常长的时间尺度下，它表现出作为有序液体的扩散运动。在这些时间尺度之间，氢键网络重排在空间上间歇地局部发生，涉及数十个水分子的局部集体运动，伴随着大的能量波动。各种实验技术来观察间歇集体运动在水中的影响进行了讨论。特别强调的是高阶非线性 ...更多信息 因为这些方法处理系统的相空间动力学。已经有深入的理论研究提出应用回声型实验，即非共振五阶（二维（2D）拉曼）光谱来区分液体动力学中的均匀和非均匀元素。(2)氢键网络重排（HBNR）有助于质子在水中的转移，使一些水分子成为三配位的。质子转移发生在这些三配位的水分子上。另一方面，质子化的水分子在冰中是四配位的，但它与第四配位的水分子的相互作用是排斥的（而与前三个的相互作用是吸引的）;几何上是四配位的，能量上是三配位的。由于与第四个水分子的这种排斥作用，O-（H）-O与其他三个水分子的距离变短，因此即使在冰中也可以发生容易的质子转移，而不会引起明显的HBNR。2（3）分析了水分子解离的机理。在液态水中，水分子分解为H^+和OH（离子通道）。然而，在气相中，已知水分离成两个自由基，H和OH。该自由基通道比离子通道稳定约290 kcal/mol。在水中，离子通道通过水合作用广泛稳定，因此水产生pH = 7。研究还发现，在超临界水中，尽管水分子密度较小，但水合作用比在水中强，因此离子通道变得更加稳定。(4)本文采用分子动力学模拟方法研究了液态水的冻结机理.将一个小的冰结构单元放置在模拟箱的中心，监测其周围形成有序氢键网络的过程。发现在一定的诱导时间后，晶化过程突然发生。进行了各种分析，以发现氢键网络如何在这种冻结机制中生长。少

项目成果

斉藤真司: "Off-Resonant Fifth Order Nonlinear Response of Water and CS_2;Analysis Based on Normal Modes" J.Chem.Phys.108. 240-251 (1998)

Shinji Saito：“水和 CS_2 的非共振五阶非线性响应；基于正则模态的分析”J.Chem.Phys.108（1998）。

T.Komatuzaki and I.Ohmine,: "′Proton Transfer in Liquid Watar II ; A semiempirical Method Describing the Potential Energy Surface′," Molecular Simulation. 16. 321-344 (1996)

T. Komatuzaki 和 I. Ohmine，“‘液体 Watar II 中的质子转移；描述势能表面的半经验方法’”，分子模拟，16. 321-344 (1996)。

A.Baba,Y.Hirata S.Saito and I.Ohmine: "′Fluctuation,Relaxation and Rearrangement Dynamics of a Model(H20)20 Cluster : Non-Statistical Dynamical Behavior" J.Chem.Phys.106. 3329-3337 (1997)

A.Baba、Y.Hirata S.Saito 和 I.Ohmine：“模型 (H20)20 簇的波动、松弛和重排动力学：非统计动态行为”J.Chem.Phys.106（ 1997）

Akinori Baba, Yoshihiro Hirata, Shinji Saito, Iwao Ohmine and David Wales: "Fluctuation, Relaxation and Rearrangement Dynamics of a Model (H_2O)_<20> Cluster ; Non-Statistical Dynamical Behavior" J.Chem.Phys.106. 3329-3337 (1997)

Akinori Baba、Yoshihiro Hirata、Shinji Saito、Iwao Ohmine 和 David Wales：“模型 (H_2O)_<20> 簇的波动、松弛和重排动力学；非统计动态行为”J.Chem.Phys.106。

Shinji Saito: "Off-Resonant Fifth Order Nonlinear Response of Water and CS_2; Analysis Based on Normal Modes" J.Chem.Phys.108. 240-251 (1998)

Shinji Saito：“水和 CS_2 的非共振五阶非线性响应；基于简正模态的分析”J.Chem.Phys.108。