Studies on Characteristic Properties of Supercritical Fluids from the View Point of Fluctuation

从涨落角度研究超临界流体的特性

• 批准号: 13440173
• 负责人: NISHIKAWA Keiko
• 金额: $ 11.07万
• 依托单位: Chiba University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 2001
• 资助国家: 日本
• 起止时间: 2001 至 2002
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-13440173/
• 关键词: supercritical fluids; supercritical solutions; fluctuation; small-angle X-ray scattering; Raman scattering; dynamic light scattering; active region; swelling; テラヘルツ電磁波

Supercritical fluids are characterized by large inhomogeneity of molecular distribution. The density fluctuation is a suitable parameter for quantitative and direct description of the inhomogeneity. We have comprehensively investigated the density fluctuation of several kinds of supercritical fluids by means of small-angle X-ray scattering (SAXS) experiments and have found the following facts. .(i)The density fluctuation forms a ridge when the contour map of their values is drawn in a phase diagram. (ii)The ridge corresponds to extrema of the various physical quantities of supercritical fluids, which are related to the second derivatives of the Gibbs free energy. (iii)The rate of increase in solubility becomes maximum on the ridge. Namely, the ridge separates the supercritical region into two, regions, in which the solubility is extremely different, (iv) The rate constants or equilibrium constants of various chemical reactions in supercritical fluids show singular behaviors on the ridge. It is concluded that the density fluctuation is one of the most fundamental factors which determine properties of supercritical fluids and its ridge is the boundary which separates, the supercritical region into two.

超临界流体的特点是分子分布的极大不均匀性。密度波动是定量和直接描述不均匀性的合适参数。我们通过小角X射线散射（SAXS）实验综合研究了几种超临界流体的密度涨落，并发现了以下事实。 (i)当在相图中绘制其值的等高线图时，密度波动形成脊。 (ii)脊对应于超临界流体的各种物理量的极值，这些极值与吉布斯自由能的二阶导数有关。 (iii)溶解度增加率在脊处达到最大。即，脊将超临界区域分成两个区域，其中溶解度极其不同，（iv）超临界流体中各种化学反应的速率常数或平衡常数在脊上表现出奇异的行为。结果表明，密度涨落是决定超临界流体性质的最基本因素之一，其脊线是将超临界区域一分为二的分界线。

项目成果

T. Morita, K. Kusano, K. Nishikawa et al.: "Titanium Sample Holder for SAXS Measurements of Supercritical Aqueous Solutions"Rev. Sci. Instrm. 72. 3013-3018 (2001)

T. Morita、K. Kusano、K. Nishikawa 等人：“用于超临界水溶液 SAXS 测量的钛样品架”Rev。

K.Saitow, K.Nishikawa et al.: "Tershertz Absorptins Spectra of Sapercritical CHF_3 to Investigate Local Structure through Rotatinul and Hindered Rotational Motions"Chem.Phys.Lett.. 341. 86-92 (2001)

K.Saitow、K.Nishikawa 等人：“通过旋转和受阻旋转运动研究局部结构的超临界 CHF_3 的 Tershertz 吸收光谱”Chem.Phys.Lett.. 341. 86-92 (2001)

T.Koga, K.Nishikawa et al.: "Density-Fluctuation-Induced Swelling of Polymer Thin Films in Carbon Dioxide"Physical Review Letters. 89・12. 125506-1-125506-4 (2002)

T.Koga、K.Nishikawa 等人：“二氧化碳中聚合物薄膜的密度波动引起的膨胀”物理评论快报 89・12（2002 年）。

K. Nishikawa, K. Kusano, A.A. Arai and T. Morita: "Density Fluctuation of a van der Waals Fluid at Supercritical State"J. Chem. Phys. 118. 1341-1346 (2003)

K. 西川、K. 草野、A.A.

K. Nishikawa, H. Ochiai, K. Saitow and T. Morita: "Static Inhomogeneity of Supercritical Ethylene Studied by Small-Angle X-ray Scattering"Chem. Phys. 286. 421-430 (2003)

K. Nishikawa、H. Ochiai、K. Saitow 和 T. Morita：“通过小角 X 射线散射研究超临界乙烯的静态不均匀性”Chem。