Studies of Thin Film Water

印第安纳州大学的乔治尤因得到实验物理化学计划的支持，进行旨在量化模型绝缘体表面上薄膜水的独特热力学性质的研究，主要是通过红外光谱法。 这些性质包括自由能、焓值和熵值、凝固点（如果膜确实凝固）以及在膜内形成气体笼形水合物时的相关系。 此外，光谱研究，连同理论合作，预计将产生结构信息的分子取向和氢键网络从亚单层到多层adlayers的水。 模型绝缘体表面将包括与离子（例如氧化镁）、共价（例如二氧化硅）和分子（例如聚乙烯）衬底相关的那些。 接近其熔点的冰作为基质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-蒸汽界面形成二氧化硫包合物的研究可以提高对地球极地地区雪异常吸收二氧化硫的性质的理解。在自然环境中，许多常见的物质都被水薄膜覆盖，包括接近熔点的冰。 与其他纳米结构一样，水薄膜表现出与大量液态水不同的行为。这项研究将探索这些无处不在的薄膜的重要特性。结果预计将影响薄水膜的性质的基本问题，并将在环境科学中的许多问题有关。 薄水膜在云的形成、土壤性质和固体（例如作为盐、洗涤剂和肥料）中的结块问题中发挥重要作用的应用实例。

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).