文章基本信息

标题：Interface-Induced Ordering of Gas Molecules Confined in a Small Space
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作者：Yi-Hsien Lu ; Chih-Wen Yang ; Chung-Kai Fang 等
期刊名称：Scientific Reports
电子版ISSN：2045-2322
出版年度：2014
卷号：4
DOI：10.1038/srep07189
出版社：Springer Nature
摘要：The thermodynamic properties of gases have been understood primarily through phase diagrams of bulk gases. However, observations of gases confined in a nanometer space have posed a challenge to the principles of classical thermodynamics. Here, we investigated interfacial structures comprising either O₂ or N₂ between water and a hydrophobic solid surface by using advanced atomic force microscopy techniques. Ordered epitaxial layers and cap-shaped nanostructures were observed. In addition, pancake-shaped disordered layers that had grown on top of the epitaxial base layers were observed in oxygen-supersaturated water. We propose that hydrophobic solid surfaces provide low-chemical-potential sites at which gas molecules dissolved in water can be adsorbed. The structures are further stabilized by interfacial water. Here we show that gas molecules can agglomerate into a condensed form when confined in a sufficiently small space under ambient conditions. The crystalline solid surface may even induce a solid-gas state when the gas-substrate interaction is significantly stronger than the gas-gas interaction. The ordering and thermodynamic properties of the confined gases are determined primarily according to interfacial interactions.