离子在水性纳米滴中的结构和电场效应
James S Prell1, Jeremy T O'Brien, Evan R Williams
1Department of Chemistry, University of California, Berkeley, California 94720-1460, USA.
Journal of the American Chemical Society
|March 17, 2011
概括
红外光分离光谱显示,离子-水集群表现出大量的水网络. 该研究强调了离子表面上特定的结水分子的普遍存在及其对水结构的影响.
科学领域:
- 物理化学 物理化学
- 频谱学是一种光谱学.
- 计算化学计算化学
背景情况:
- 了解离子附近的水的结构对于各种化学和生物过程至关重要.
- 之前的研究已经研究了离子-水相互作用,但在分子水平上获得详细的结构信息仍然具有挑战性.
研究的目的:
- 用组合红外光解离 (IRPD) 光谱学研究离子-水集群中的水网络结构.
- 确定水分子在各种阳离子和阳离子表面的键特性.
- 探索离子电荷和类型对水网结构的影响.
主要方法:
- 集成红外光解离 (IRPD) 光谱检测对M(H2O) n集群 (n=35-37) 进行了一系列的 (M) 离子,包括化物,二碳酸盐,离子和各种金属离子.
- 在延伸区域 (2950-3800厘米(-1)) 在133 K.记录了光谱.
- 使用两个静电模型的计算模拟被用来解释实验频谱.
主要成果:
- 频谱的结合OH区域显示了一个单一的,广泛的特征,表明大量的水网络类似于液态水而不是冰.
- 自由OH区域由水分子接受两个并捐赠一个键 (AAD水分子) 的峰值占主导地位,这表明它们在离子表面的丰富性.
- AAD自由OH伸展带的频率呈现出离子电荷的近线性转移,与斯特克效应一致,并允许推断到大量液态水面.
结论:
- 离子显著地塑造了水网络,延伸到第三和第四个溶解,甚至在很远的距离上也影响了水结构.
- 该研究提供了对水分子在离子表面的优先结安排的见解.
- 虽然静电模型在质量上复制了光谱特征,但为了获得定量准确性,需要在处理偏振和振动合方面取得进一步的进展.
相关概念视频
The Electrical Double Layer
In the region where two bulk phases meet, an intricate electric charge distribution arises due to charge transfer, ion adsorption, molecular orientation, and charge distortion. This complex distribution is commonly referred to as the electrical double layer.When a solid electrode interfaces with ions in an electrolyte solution, the speed of electron transfer dictates the rates of oxidation and reduction. The electrode acquires a charge through the escape of atoms into the solution as cations or...
Induced Electric Dipoles
A permanent electric dipole orients itself along an external electric field. This rotation can be quantified by defining the potential energy because the external torque does work in rotating it. Then, the potential energy is minimum at the parallel configuration and maximum at the antiparallel configuration. While the former is a stable equilibrium, the latter is an unstable equilibrium.
Since the absolute value of potential energy holds no physical meaning, its zero value can be chosen as per...
Since the absolute value of potential energy holds no physical meaning, its zero value can be chosen as per...
Crystal Field Theory - Octahedral Complexes
Crystal Field Theory
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
Theory of Strong Electrolytes
The interionic forces of the strong electrolytes depend on the solvent's dielectric constant, which is the ability of a solvent to store electrical energy, based on its polarizability. and the solution's concentration. In high-dielectric solvents and in dilute solutions, weak electrostatic forces keep ions apart. However, in low-dielectric solvents or concentrated solutions, stronger interionic forces may cause ions to pair up as ionic doublets despite being fully ionized. The theory of strong...
Electrolytes: van't Hoff Factor
Colligative Properties of ElectrolytesThe colligative properties of a solution depend only on the number, not on the identity, of solute species dissolved. The concentration terms in the equations for various colligative properties (freezing point depression, boiling point elevation, osmotic pressure) pertain to all solute species present in the solution. Nonelectrolytes dissolve physically without dissociation or any other accompanying process. Each molecule that dissolves yields one dissolved...
Electrochemical Systems
Electrochemical systems provide a fascinating insight into the dynamic interplay of charged species within various phases. One notable example is the interaction between a membrane permeable to K⁺ ions but not to Cl⁻ ions, separating an aqueous KCl solution from pure water. As K⁺ ions diffuse through the membrane, they generate net charges on each phase, leading to a potential difference between them.Similarly, when a piece of Zn is immersed in an aqueous ZnSO₄ solution, the Zn metal, composed...


