水分子的化学式仍然应该是H2O

本刊曾在《物理新闻与动态》栏（2003，32（12）：841）上报道过德国柏林技术大学关于在短时间尺度（几阿秒）下探测到水分子的化学式不是H2O，而是H1．5O，当时这个研究成果曾使物理学界很为震动，因而有更多的科学家投身于此项研究中，最近美国Ben Gurion大学的科学家们利用高能中子对纯净的D2O水进行轰击，并在短时间尺度内（10^-17—10^-18s）测量它的反常光散射，     

重水分子伸缩振动谱的非线性量子理论计算

用非线性量子理论中的离散自陷方程对蒸汽态和液态重水分子在高激发态下的伸缩振动能谱进行了计算。从中发现重水分子的振动能谱分布具有许多有趣的特点。计算所得到的结果对研究重水在高压状态下的特性具有重要的应用价值。     

利用扩展系综法计算水的自由能

利用扩展系综法得到了正则系综下水的TIP4P模型的自由能值为-21．485±0．035kJ/mol， 并与其他方法所得的结果作了比较.提出了选择该方法中关键参数(平衡因子)的有效方法， 并讨论了该方法的可移植性. 关键词： 自由能 TIP4P水模型 扩展系综 分子动力学模拟 水分子团     

外电场作用下三元环状水分子团簇的特性研究

采用了HartreeFork自洽场方法在321G水平上研究了0～0.01a.u.的外电场对三元环状水分子团(H2O)3基态能量和电偶极距的影响规律,分析了由外电场产生的HellmanFeynman(HF)力(内力和外力)和在这个力的平衡作用下的团簇的稳定结构,结果表明,外电场的大小对三元环状水分子团簇(H2O)3这些性质有明显的影响.通过高斯计算可以得出,在所加的电场范围内,随着外电场的增大总能量下降,电偶极距增大,结构相对更稳定;外电场引起团簇中各个原子的电荷密度改变,导致了各个原子所受的静电力随之变化.     

以q空间法研究水分子在水晶体中之扩散及其结构

在核磁共振中的脉冲梯度自旋回响法(pulsed gradient spin echo,PGSE)常用来测量溶液中分子或离子的扩散现象,近年来利用PGSE q空间法对多孔隙物质的系统扩散研究。观察到类似绕射效应,在此工作中我们尝试以q空间法直接观察眼球水晶体中的纤维细胞组织和水分子扩散间的关系,实验结果显示,从类似绕射纹图可了解纤维细胞蜂巢式排列结构。     

A Quasi-One-Dimensional Model for a Chain of Water Molecules on the Nanometer Scale

Water confined into the interior channels of narrow carbon nanotubes or transmembrane proteins can form collectively oriented molecular chains held together by tight hydrogen bonds. We develop a quasi-one-dimensional model for a chain of water molecules which interact with each other via the Coulomb and power-like repulsive interactions. We explore the equilibrium property of the water chain and derive an exact analytical expression for the total interaction energy of the water chain, denoted by W（0）int. It is found that W（0）int is minimal when the distance between the two neighboring water molecules in a hydrogen-bonded chain is equal to 0.265 nm. The model is expected to be useful for studying analytically the properties of single-file water molecules inside water channels, such as the concerted motion of water molecules.     

用群论方法确定H2O的振动模式

用群论方法给出Ｈ２Ｏ分子的三种简正振动模式的数学表达式，并对有关计算作进一步分析讨论放补充修正。     

H2O的光解离：单分子解离的出色例子

利用氢原子里德堡态标记的时间飞渡技术研究了Ｈ２Ｏ在１２１和１５７ｎｍ的光解离，并测量出了这两个波长下的ＯＨ产物的振动和转动态分布。实验结果表明，１２１ｎｍ下Ｈ２Ｏ光解离主要产生高转动激发的ＯＨ只有很少振动激发。而在１５７ｎｍ的光解产生ＯＨ的振动激发只有很少转动激发。研究表明高振动激发ＯＨ（ｖ≥２）的相对布居在ＬＩＦ测量的工作中被严重低估了，因此指出ＬＩＦ技术定量测量产物ＯＨ的振动态分布是有问题的。     

Synthesis,Crystal Structure and Optical Properties of a Cerium（IV） Complex with Chelidamic Acid

A new cerium complex, （C7H8）[Ce（C7H3NO5）2（H2O）3]·2H2O or （C7Hs）[Ce（HChel）2· （H2O）3]·2H2O （1, H3Chel = 4-hydroxypyridine-2,6-dicarboxylic （chelidamic） acid）, has been prepared by the hydrothermal reaction, and its crystal structure was determined based on single-crystal diffraction data. Compound I crystallizes in monoclinic, space group P21/c with a = 12.4267（9）, b = 10.8195（7）, c = 19.5650（13）A, β = 92.898（3）°, V = 2627.2（3） A^3, Dc = 1.733 g/cm^3, Z = 4, Mr = 685.55, μ = 1.809 mm^-1, λ（MoKa） = 0.71073A and F（000） = 1372. The final R = 0.0455 and wR = 0.1984 for 5983 observed reflections with I 〉 2σ（I）, and R = 0.0490 and wR = 0.2053 for all data. Complex 1 contains one cerium ion, two chelidamic acid ligands, three coordinated water molecules, one discrete toluene molecule, and two discrete water molecules. The Ce（IV） ion is nine-coordinate with the coordination polyhedron made up of four oxygen atoms and two nitrogen atoms from two tridentate chelating chelidamic acid ligands, and three coordinated water molecules. A three-dimensional network is formed by the H-bonds. Moreover, optical properties are investigated and the results show that this complex has sharp optical absorption at 221,396 and 571 nm but no marked fluorescent emission.     

MP2 Study on the Proton Transfer Mechanism of Glycine Assisted by Water

The geometries of glycine-nH2O （n = 1-5） complexes and the transition states of proton transfer in glycine-H2O system were calculated at the MP2/6-31＋＋G＊＊//MP2/6-31G＊ level, upon which we discovered the proton transfer mechanisms, including the number of water molecules necessary for the stabilization of zwitterions and the effect of increasing water molecules on the proton transfer. To our interest, we found that only one water molecule can stabilize the zwitterions; in addition, with the increment of water molecules, the activation energy of positive reaction decreases and that of reverse reaction increases gradually. Glycine will be ionized completely while the water molecules reach to a certain number.