On the dynamics and phase properties of water molecules spread over 2D space

采用准弹性中子散射光谱、介电测量和核磁共振测量等方法研究了水分子在二维场中扩散的动力学性质。(1)在羟基化的氧化铬表面，水分子通过形成均匀的二维相被吸附，其中观察到晶格气凝相（液体或固体）平衡。本研究的主要目的是在2d临界温度（30ºC）以上和以下分配凝聚相。根据准弹性中子散射，发现水分子在二维临界温度以下有旋转运动，但没有平移扩散。电介质的测量结果证实了这一点，即在相同的温度范围内会发生某种介电弛豫。在二维临界温度（47.6‰）以上的准弹性中子散射测量得到平移扩散系数3.1*10^<-10> m^2s^<-1>。这些事实表明，在低于2D临界温度的情况下，吸附的是固体水。乙醇吸附与h2o吸附比较，在单层中没有二维缩合现象，而在双层中有特殊的关联。使用Cerius2程序对水和甲醇的吸附进行蒙特卡罗模拟，得到了与红外测量推测的结构不同的结构。(2)采用准弹性中子散射、核磁共振、红外光谱等方法研究了层间水分子在五氧化二钒水合物中的动力学性质。中子散射测量证实了水分子在二维受限空间中扩散，并给出了双层水的自扩散系数7.2m^2s^<-1>。这支持了Dianoux等人提出的在受限空间内自扩散过程的观点。吸附速率分析表明，颗粒的扩散路径在几毫米范围内。氨以分子和离子（铵）两种模式插入层间。少

Dynamic properties of water molecules spread in a two-dimensional field were studied by applying the quasi-elastic neutron scattering spectroscopy, dielectric measurements, and NMR measurements.(1) On a hydroxylated chromium oxide surface water molecules are adsorbed by forming the homogeneous two-dimensional phase, in which lattice gas-condensed phase (liquid or solid) equilibrium is observed. Main purpose of the present study is to assign the condensed phase above and below the 2D-critical temperature (30ﾟC). According to the quasi-elastic neutron scattering there found rotational motion of water molecules below the 2D critical temperature but no translational diffusion. Dielectric measurements supported this with the fact that some kind of dielectric relaxation occurs in the same temperature range. Quasi-elastic neutron scattering measurements above 2D critical temperature (47.6ﾟC) gave translational diffusion coefficient 3.1*10^<-10> m^2s^<-1>. These facts indicate that adsorbed ph … More ase below the 2D critical temperature is a solid water. Alcohol adsorption was done comparatively with the H_2O adsorption, in which two-dimensional condensation was not observed in a monolayr but special association was found in double layr range. Monte Carlo simulations for the adsorption of water and methanol using the program Cerius2 gave the structure different from the one presumed from the IR measurements.(2) Dynamic properties of interlayr water molecules in the layred vanadium pentoxide hydrate were studied by quasi-elastic neutron scattering, NMR,and FT-IR.C_<2v> rotation axis of monolayr water molecule leans from c-axis by 18ﾟ. Neutron scattering measurements substantiate that water molecules diffuse in a two dimensionally confined space and give the self-diffusion coefficient 7.2m^2s^<-1> for double layr water. This supports the idea proposed by Dianoux et al for the self-diffusion process in a confined space. Analysis of the diffusion observed by adsorption rate measurements suggested that the diffusion path of the particle ranges a few mm. Ammonia was intercalated between the layrs in two modes, molecular and ionized (ammonium) forms. Less