Studies of Thin Film Water

印第安纳大学的George Ewing在实验物理化学项目的支持下开展了一项研究，旨在量化模型绝缘体表面薄膜水的独特热力学性质，主要是通过红外光谱。这些性质包括自由能、焓和熵值、凝固点（如果薄膜确实冻结的话），以及薄膜内气体笼形水合物形成的相关系。此外，光谱学研究和理论合作有望获得分子取向和从亚单层到多层水的氢键网络的结构信息。模型绝缘体表面将包括那些与离子（如氧化镁）、共价（如二氧化硅）和分子（如聚乙烯）衬底相关的表面。接近熔点的冰作为基底将受到特别密切的关注。对气态二氧化硫引起的冰的表面融化和在冰-蒸汽界面形成的二氧化硫包合物的研究可以提高对地球极地地区雪异常二氧化硫吸收性质的理解。在自然环境中，水的薄膜覆盖着许多常见的物质，包括接近其熔点的冰。像其他纳米结构一样，水薄膜表现出与大块液态水不同的行为。本研究将探讨这些无处不在的电影的重要特性。研究结果预计将影响到水薄膜性质的基本问题，并将与环境科学中的许多问题相关。水薄膜在云的形成、土壤特性和固体（如盐、洗涤剂和肥料）中的结块问题等应用中发挥重要作用的例子。

George Ewing of Indiana University is supported by the Experimental Physical Chemistry Program to carry out research that aims to quantify the unique thermodynamic properties of thin film water on model insulator surfaces, principally by infrared spectroscopy. These properties include free energy, enthalpy and entropy values, freezing points (if indeed films do freeze), and phase relationships in the formation of gas clathrate hydrates within the films. In addition, spectroscopic studies, together with theoretical collaborations, are expected to yield structural information on molecular orientations and hydrogen bonding networks from submonolayer to multilayer adlayers of water. The model insulator surfaces will include those associated with ionic (such as magnesium oxide), covalent (such as silica), and molecular (such as polyethylene) substrates. Ice near its melting point will receive particularly close attention as a substrate. Surface melting studies of ice induced by gaseous sulfur dioxide and formation of the sulfur dioxide-clathrate at the ice-vapor interface could improve understanding of the nature of anomalous sulfur dioxide uptake by snow in the Earth's polar regions. Thin films of water coat many common substances in the natural environment, including ice near its melting point. Like other nanostructures, thin films of water exhibit behavior that is different from that of bulk liquid water. This research will explore significant properties of these ubiquitous films. Outcomes are expected to impact fundamental issues in the properties of thin water films, and will be relevant to many problems in environmental science. Examples of applications where thin water films play an important role are in cloud formation, soil properties, and caking problems in solids (such as salt, detergents, and fertilizer).