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.

最近在介观材料方面的突破使固液界面科学重新焕发了活力，并将其重点从体相热力学描述转移到分子间力。 该项目的目标是建立一个中央设施，通过原子力显微镜（AFM）测量和绘制分子间和表面力，并通过学生的研究，发现固体表面在相邻液相（液相外延）中引导界面有序形成的作用。首先，在不同的基板上的固相的成核和过度生长将在亚稳溶液中通过原位成像进行研究。 研究将集中在生长形态的差异（润湿与岛形核与针状生长）作为基板和覆盖层之间的兼容性的函数。第二，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和界面胶束对溶致相的模板作用。 观察到的界面形态将与理论计算的基础上优化的胶束晶格和基板的净相互作用能。 温度在结构相变中的作用将使用现有的温度控制单元进行探索，该单元在水溶液的温度范围内操作。 参加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/技术劳动力市场做好准备。%与固体表面接触的液体膜的部分有序是从晶体生长到介观材料合成到边界层润滑的界面过程的核心。 本计画的目标是借由原子力显微镜（AFM）量测分子间的作用力，以揭示界面有序形成的机制。 该技术使用亚显微尖端或触针来测量分子间力，并通过绘制整个表面的力变化来在原子尺度上对表面进行成像。 学生实验员将使用力测量和成像在液体环境中，以调查固体表面的作用，从解决方案成核固体和液晶相。 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真实的时间和分子分辨率成像。 研究将集中在生长形态的差异与衬底和覆盖层的原子结构之间的不匹配程度。 也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作用。 界面层的观察到的结构将与理论计算相关联，基于优化的表面和表面活性剂聚集层的净相互作用能。 温度对这些阶段的影响将使用一个特殊的样品池目前正在运行进行调查。 这些结果有望揭示新的界面过程，如去污和先进材料的自组装合成。 这项研究将针对为学术界、工业界和政府的科学/技术就业做好准备的学生进行。