CAREER: Discovering the Mechanisms of Liquid Phase Epitaxy and Bringing Intermolecular Forces to the Physics Curriculum

职业：发现液相外延机制并将分子间力引入物理课程

• 批准号: 0094385
• 负责人: Srinivas Manne
• 金额: $ 45万
• 依托单位: University of Arizona
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-08-01 至 2006-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0094385&HistoricalAwards=false
• 关键词: CAREER; Discovering; Mechanisms; Liquid; Phase

Recent breakthroughs in mesoscopic materials have reinvigorated the science of solid-liquid interfaces and shifted its emphasis from bulk thermodynamic descriptions to intermolecular forces. The goals of this project are to establish a central facility for the measurement and mapping of intermolecular and surface forces by atomic force microscopy (AFM) and, through student research, to discover the role of solid surfaces in directing interfacial order formation in an adjoining liquid phase (liquid phase epitaxy). First, the nucleation and overgrowth of a solid phase over a different substrate will be investigated by in-situ imaging in metastable solutions. Studies will focus on differences in growth morphology (wetting vs. island nucleation vs. needle growth) as a function of compatibility between substrate and overlayer. Second, force measurements and soft contact imaging will explore the interfacial self-assembly of surfactant solutions and the templating of lyotropic phases by interfacial micelles. Observed interfacial morphologies will be correlated with theoretical calculations based on optimizing the net interaction energy of the micelle lattice and substrate. The role of temperature in structural phase transitions will be explored using an existing temperature-control cell that operates over the aqueous range of temperatures. The students participating in this research will be trained in a contemporary area of condensed matter physics and will thereby be prepared to enter the scientific/technical workforce.%%%The partial ordering of a liquid film in contact with a solid surface is central to interfacial processes ranging from crystal growth to mesoscopic materials synthesis to boundary layer lubrication. The goals of this project are to uncover the mechanisms of interfacial order formation by the measurement and mapping of intermolecular forces by atomic force microscopy (AFM). This technique uses a sub-microscopic tip or stylus to measure intermolecular forces and to image surfaces at atomic scales by mapping force variations across the surface. Student experimentalists will use force measurements and imaging in liquid environments to investigate the role of solid surfaces in nucleating solid and liquid crystalline phases from solutions. Crystal growth of one mineral on a second, closely matched solid will be imaged in real time and at molecular resolution in supersaturated solutions. Studies will focus on differences in growth morphology versus the degree of mismatch between the atomic structure of substrate and overlayer. The nucleation of liquid crystalline phases of surfactants or detergents by solid surfaces will also be investigated. The observed structures of interfacial layers will be correlated with theoretical calculations, based on optimizing the net interaction energy of the surface and surfactant aggregate layer. The effects of temperature on these phases will be investigated using a special sample cell currently under operation. These results are expected to shed new light on interfacial processes such as detergency and the synthesis of advanced materials by self-assembly. This research will be conducted with students who will be prepared for scientific/technical employment in academia, industry, and government.

介观材料的最新突破重振了固液界面科学，并将其重点从本体热力学描述转移到分子间力。 该项目的目标是建立一个中心设施，用于通过原子力显微镜（AFM）测量和绘制分子间力和表面力，并通过学生研究，发现固体表面在引导相邻液体中界面有序形成中的作用相（液相外延）。首先，将通过亚稳态溶液中的原位成像来研究固相在不同基底上的成核和过度生长。 研究将重点关注生长形态的差异（润湿、岛形成核、针状生长）作为基底和覆盖层之间兼容性的函数。其次，力测量和软接触成像将探索表面活性剂溶液的界面自组装以及界面胶束的溶致相模板化。 观察到的界面形态将与基于优化胶束晶格和基材的净相互作用能的理论计算相关联。 将使用在水相温度范围内运行的现有温度控制单元来探索温度在结构相变中的作用。 参与这项研究的学生将接受当代凝聚态物理领域的培训，从而为进入科学/技术队伍做好准备。%%%与固体表面接触的液膜的部分有序性是界面的核心从晶体生长到介观材料合成再到边界层润滑的过程。 该项目的目标是通过原子力显微镜（AFM）测量和绘制分子间力来揭示界面有序形成的机制。 该技术使用亚显微尖端或触笔来测量分子间力，并通过绘制整个表面上的力变化来在原子尺度上对表面进行成像。 学生实验人员将在液体环境中使用力测量和成像来研究固体表面在溶液中固相和液晶相成核中的作用。 一种矿物在第二种紧密匹配的固体上的晶体生长将在过饱和溶液中以分子分辨率实时成像。 研究将集中于生长形态的差异与衬底和覆盖层原子结构之间的不匹配程度。 还将研究表面活性剂或洗涤剂的液晶相通过固体表面的成核。 基于优化表面和表面活性剂聚集层的净相互作用能，观察到的界面层结构将与理论计算相关联。 将使用目前正在运行的特殊样品池来研究温度对这些相的影响。 这些结果有望为去污力和通过自组装合成先进材料等界面过程提供新的线索。 这项研究将由那些为学术界、工业界和政府部门的科学/技术就业做好准备的学生进行。