Studies of Physical Adsorption

物理吸附研究

• 批准号: 8718771
• 负责人: Milton Cole
• 金额: $ 91.5万
• 依托单位: Pennsylvania State Univ University Park
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1988
• 资助国家: 美国
• 起止时间: 1988-02-01 至 1991-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=8718771&HistoricalAwards=false
• 关键词: Studies; Physical; Adsorption

Physical adsorption refers to the state when molecules are weakly bound to surfaces (binding energies less then one-tenth of an electron volt). The many phenomena observed in physisorbed films have attracted the attention of a diverse group of scientists because they reveal fundamental behavior of matter in a different way from bulk systems. This program presents a multi-facetted attack on a set of problems of current interest. One broad area of focus is film structure; interesting questions include the nature of two dimensional phases (commensurate, incommensurate, orientationally ordered) and transitions between such phases, the growth of films as they become three dimensional and wetting transitions. A closely related problem involves the dynamical properties of these films. Both of these will be addressed by thermodynamic and scattering techniques, traditional probes used in bulk systems. Another fundamental area of investigation is the binding of gas molecules to surfaces; this also is to be studied by scattering. Accompanying these experiments will be theoretical studies concerned with the same issues. Included are the application of statistical mechanics to describe the collective phenomena associated with film ordering. Computer simulation is a particularly powerful tool to explain and predict these properties, as well as test theoretical hypotheses about the force laws. The systems to be considered include both monatomic and polyatomic adsorbate species. While the popular graphite substrate will receive some attention, magnesium oxide and other substrates will get somewhat greater emphasis. The "compound" system of solid and monolayer film will be studied by both elastic and inelastic scattering probes.

物理吸附是指分子与表面弱结合的状态(结合能小于十分之一电子伏特)。在物理吸附薄膜中观察到的许多现象引起了不同科学家的注意，因为它们以不同于主体系统的方式揭示了物质的基本行为。这个节目对一系列当前感兴趣的问题进行了多方面的攻击。一个广泛的焦点领域是薄膜结构；有趣的问题包括二维相(公度、无公度、取向有序)的性质和这些相之间的转变，薄膜在转变为三维和润湿转变时的生长。一个密切相关的问题涉及到这些薄膜的动力学性质。这两个问题都将通过热力学和散射技术来解决，这些技术是散体系统中使用的传统探测器。另一个基本的研究领域是气体分子与表面的结合；这也需要通过散射来研究。伴随着这些实验，将会有与相同问题有关的理论研究。包括统计力学的应用来描述与薄膜有序相关的集体现象。计算机模拟是解释和预测这些性质以及验证力定律的理论假设的特别强大的工具。考虑的体系既包括单原子吸附物种，也包括多原子吸附物种。虽然流行的石墨衬底将受到一些关注，但氧化镁和其他衬底将受到更大的重视。用弹性和非弹性散射探头研究固体和单层膜的“复合”体系。