Enhancement of Structural Fluctuation in the Region Connecting Two Kinds of Critical Points in Temperature-Pressure-Composition Three-Dimensional Phase Diagram: Raman Studies of Benzene/CO2

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• 作者：Hideyuki Nakayama ; Miki Murai ; Mariko Tono-oka ; Kumiko Masuda ; Kikujiro Ishii
• 刊名：Journal of Physical Chemistry A
• 出版年：2007
• 出版时间：March 1, 2007
• 年：2007
• 卷：111
• 期：8
• 页码：1410 - 1418
• 全文大小：214K
• 年卷期：v.111,no.8(March 1, 2007)
• ISSN：1520-5215

文摘

Pressure dependence of Raman spectra of benzene/CO₂ two-component systems was systematically studiedat different temperatures and compositions. We estimated the magnitude of inhomogeneous component inRaman bandwidth to get information on the structural fluctuation in the system. It was found that theinhomogeneous bandwidth attains a maximum on an isothermal plane in the temperature-pressure-composition three-dimensional phase diagram when the state point crosses the line connecting the regionwhere the density fluctuation is large (the vicinity of the critical point of neat CO₂) and the region where theconcentration fluctuation in a binary system is enhanced (the vicinity of the critical solution point). Byaccumulating such data, we found that the points of large structural fluctuation comprise a sheet that includesthe extension line of the gas-liquid equilibrium line in the phase diagram of neat CO₂ and the line connectingcritical solution points of the two-component system at different temperatures. Interaction between benzeneand CO₂ molecules in the supercritical region is briefly discussed.