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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.

用吸附热、原位X射线衍射、高压吸附和普通分子吸附等方法研究了SO_2、NO、N_2、CH_4和H_2O在狭缝状碳亚纳米空间中的分子状态。超临界NO气体在磁扰动的作用下，在亚纳米空间的强分子场作用下生成（NO）_2，从而转变为准蒸汽。亚纳米空间场和吸附剂高压的作用使超临界CH_4和N_2转化为准蒸气。高分辨X射线衍射分析表明，H_2O分子组装体在亚纳米空间中的结构发生了变化，出现了扭曲的二维冰状结构，SO_2和0.8nm宽的碳狭缝孔体系中的分子组装体出现了新的相变。SO_2在碳亚纳米空间中的吸附热可划分为phi=0.6以下的增强势场恒定区和phi=0.6以上的急剧增加区。在恒定区，SO_2分子与狭缝孔的相互作用增强（约10 KJ/mol），其中包括诱导的偶极-永久偶极相互作用，表明吸附SO_2分子的偶极平行排列。这是由于SO_2分子间的相互作用引起了偶极子的转换，形成了反平行排列。使用Lennard-Jones势、镜像势近似和Stockmayr势计算的分子势支持了该模型。这种取向结构在亚纳米空间中依赖于纳米尺度的宽度，在更大的纳米空间中没有观察到上述陡峭的转变。这项研究为亚纳米空间场控制分子化学提供了新的可能性。