Pseudo Phase Transition of Molecular Assembly in a Structure- Controlled Subnanospace Having Enhanced Potential.

结构控制的亚纳米空间中分子组装的伪相变具有增强的潜力。

基本信息

批准号：
04453004
负责人：
KANEKO Katsumi
金额：
$ 4.1万
依托单位：
Chiba University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1992
资助国家：
日本
起止时间：
1992 至 1993
项目状态：
已结题

项目摘要

Molecular states of SO_2, NO, N_2, CH_4, and H_2O in carbon subnanospaces of slit shape were studied by heat of adsorption, in situ X-ray diffraction, high pressure adsorption, and ordinary molecular adsorption. Supercritical NO gas was changed into quasi-vapor through formation of (NO)_2 due to strong molecular field of the subnanospace with the aid of magnetic perturbation. Also supercritical CH_4 and N_2 was transformed to their quasi-vapor due to the subnanospace field and application of high pressure of adsorptives. The structural change of H_2O molecular assembly in the subnanospace was examined by high resolution X-ray diffraction anaysis, indicating presence of a distorted two-dimensional ice like structure.New phase transition of molecular assembly in the carbon nanospace was shown in the system of SO_2 and carbon slit pore of 0.8 nm width. The heat of SO_2 adsorption in the carbon subnanospace was divided into the constant region of enhanced potential field below phi=0.6 and an steep increase region above phi=0.6. The constant region was ascribed to enhanced SO_2-slit pore interactions (about 10 KJ/mol) including the induced dipole-permanent dipole interaction ; this indicated the parallel arrangement of dipoles of adsorbed SO_2 molecules. The steep increase was caused by the inter SO_2 molecular interaction which gives rise to conversion of the dipoles, forming the anti-parallel arrangement. The molecular potential calculation using the Lennard-Jones potential, the image potential approximation, and the Stockmayr potential supported this model. This orientation structure of the SO_2 dipoles in the carbon subnanospace depended on the micropore width ; in the greater carbon nanospace the above-mentioned steep transition was not observed. This research showed a new possibility of molecular chemistry controlled by the subnanospace field.

通过吸附热，原位X射线衍射，高压吸附和普通的分子吸附，研究了SO_2，NO，N_2，CH_4和H_2O的分子状态。超临界的气体通过磁扰动的帮助，通过（NO）_2形成（NO）_2，将其变成准蒸气。由于亚纳米空间场和吸附剂的高压应用，超临界CH_4和N_2也被转换为准蒸气。高分辨率X射线衍射Anaysis检查了亚纳米范围内H_2O分子组装的结构变化，表明存在碳纳米拼体中分子组装的新二维冰的存在，在SO_2和Carbon Slit Slit孔中显示了分子组装的新相变。 SO_2在碳亚纳米空间中的吸附热被分为PHI = 0.6以下的势场的恒定区域，而急剧上升的区域高于PHI = 0.6。将常数区域归因于增强的SO_2斜孔相互作用（约10 kJ/mol），包括诱导的偶极 - 永久偶极相互作用；这表明吸附的SO_2分子的偶极子的平行排列。陡峭的增加是由SO_2分子相互作用引起的，这会导致偶极子的转化，从而形成反行排列。使用Lennard-Jones电位的分子电势计算，图像电位近似和StockMayr电位支持该模型。碳亚纳米空间中SO_2偶极子的这种定向结构取决于微孔宽度；在更大的碳纳米空间中，未观察到上述陡峭过渡。这项研究表明，由亚纳米波接地控制的分子化学的新可能性。