Atomic Force Microscopy Studies of Tribochemical Phenomena

摩擦化学现象的原子力显微镜研究

• 批准号: 0409861
• 负责人: J. Thomas Dickinson
• 金额: --
• 依托单位: Washington State University
• 依托单位国家: 美国
• 项目类别: Continuing grant
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-07-01 至 2007-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0409861&HistoricalAwards=false
• 关键词: Atomic; Force; Microscopy; Studies; Tribochemical

We request support for a three-year project to examine the consequences of simultaneous application of chemical agents and mechanical stress to a solid surface. We explore the resulting nanometer-scale changes in surface topography due to application of combined highly localized mechanical stress (due to contact with the tip of an atomic force microscope) and exposure to appropriate solutions and solvents. These basic studies impact several technologies in that they provide underlying understanding for areas such as chemical mechanical planarization (CMP), tribochemical wear, tribo-induced redeposition, tribology in biological systems (where biological fluids serve as the active media), and nanotechnology. Any relative motion of surfaces, no matter how small, will involve dissipative forces that need to be understood and controlled in nanometer-scale devices. As device sizes shrink, the need for clean, atomically flat surfaces will become more and more pressing. Our overall goal is to develop descriptive and predictive models for asperity and substrate modification due to combined chemical, thermal, and mechanical processes.Intellectual Merit - Tribochemical phenomena are complex and poorly understood. Our approach is to simplify the system to a single asperity (the AFM tip), which we can characterize topographically and in some cases chemically, and use simple chemical systems (e.g., water). Our role in the science of stress enhanced processes is to identify the underlying mechanisms. Although we work on a nanometer scale, we are not doing nanotechnology - we support others who are doing nanotechnology. Through careful, quantitative measurements, we clarify the details of both asperity and substrate wear, and the connection between asperity wear and changes in friction with a given substrate. More subtle is a new area we have discovered, namely tip-controlled deposition of materials from saturated solution. Scanning at low contact forces in supersaturated solutions can be exploited to locally deposit crystalline material. For relatively flat surfaces with occasional pits, filling in the pits can be a much more efficient method of producing atomically flat surfaces than removing whole surface layers. We have observed fluctuations in the lateral force during scanning of relatively insoluble, ionic materials that correlate strongly with the degree of supersaturation. We propose to explore this tool as a possible probe of transient surface deposits that are expected in supersaturated solutions and to further our understanding of the fundamental mechanisms for the tip induced deposition and structuring that occurs in supersaturated solutions. An innovative, untested idea, we propose is to combine stress+chemical stimulation with exposure to radiation. The proposed radiation sources are electron beams and UV and femtosecond laser beams. Laser irradiation can be applied in situ. Following radiation exposure we seek synergisms with tribochemical stimulation. We anticipate positive results and will explore the underlying mechanisms in light of what we know about bond breaking, defect formation, and other chemical modifications generated by radiation exposure. We hope to find a new way to promote surface modification.Broader impacts. In addition to a graduate student, this work will involve 4-6 undergraduates a year, and at least one high school student. We expect most of our students, as in the past, to publish their results in peer-reviewed journals. These efforts also fulfill undergraduate department and honors college theses requirements. As undergraduate advisor for physics and honors physics instructor, the PI often influences women and minorities to become science/technology majors, double majors, and/or become involved early in our research projects. The research itself, through fundamental understanding, provides benefits to society in need of reduced wear, longer life, and environmentally friendly processes and systems. Efforts in nanotechnology involving moving interfaces and/or needs for atomically flat, clean surfaces or tip/solution generated structures also benefit from our studies.

我们请求支持一个为期三年的项目，研究同时对固体表面施加化学剂和机械应力的后果。我们探索所产生的纳米尺度的变化，由于应用相结合的高度局部化的机械应力（由于与原子力显微镜的尖端接触）和暴露于适当的解决方案和溶剂的表面形貌。这些基础研究影响了多项技术，因为它们为化学机械平面化（CMP）、摩擦化学磨损、摩擦诱导的再沉积、生物系统中的摩擦学（其中生物液体作为活性介质）和纳米技术等领域提供了基础认识。表面的任何相对运动，无论多么小，都将涉及耗散力，需要在纳米级器件中理解和控制。随着器件尺寸的缩小，对清洁、原子级平坦表面的需求将变得越来越迫切。我们的总体目标是开发描述性和预测性模型，用于描述由于化学、热和机械过程的组合而导致的粗糙表面和基材改性。知识优势-摩擦化学现象非常复杂，人们对其了解甚少。我们的方法是将系统简化为单个粗糙体（AFM针尖），我们可以从形貌上和在某些情况下化学上表征该粗糙体，并使用简单的化学系统（例如，水）。 我们在压力增强过程科学中的作用是确定潜在的机制。虽然我们在纳米尺度上工作，但我们不是在做纳米技术-我们支持其他正在做纳米技术的人。通过仔细的定量测量，我们澄清了粗糙和基体磨损的细节，以及粗糙磨损和给定基体摩擦变化之间的联系。更微妙的是我们发现的一个新领域，即从饱和溶液中尖端控制材料沉积。在过饱和溶液中以低接触力进行扫描可用于局部存款结晶材料。对于偶尔有凹坑的相对平坦的表面，填充凹坑可能是比去除整个表面层更有效的产生原子级平坦表面的方法。我们已经观察到波动的横向力在扫描过程中的相对不溶性，离子材料，强烈相关的过饱和度。我们建议探索这个工具作为一个可能的探头的瞬态表面存款，预计在过饱和的解决方案，并进一步了解的基本机制，尖端诱导沉积和结构发生在过饱和的解决方案。我们提出了一个创新的、未经测试的想法，即将联合收割机压力+化学刺激与辐射结合起来。建议的辐射源是电子束和紫外线和飞秒激光束。激光照射可以在原位应用。在辐射暴露后，我们寻求与摩擦化学刺激的协同作用。我们预期会有积极的结果，并将根据我们对键断裂、缺陷形成和辐射暴露产生的其他化学修饰的了解，探索潜在的机制。我们希望找到一种新的方法来促进表面改性。除了一名研究生外，这项工作每年将涉及4-6名本科生，以及至少一名高中生。我们希望我们的大多数学生，像过去一样，在同行评议的期刊上发表他们的结果。这些努力也满足本科部门和荣誉大学论文的要求。作为物理学和荣誉物理导师的本科生顾问，PI经常影响女性和少数民族成为科学/技术专业，双专业和/或早期参与我们的研究项目。研究本身，通过基本的理解，为需要减少磨损，延长寿命和环境友好型工艺和系统的社会提供了好处。在纳米技术方面的努力，包括移动界面和/或对原子级平坦、清洁表面或尖端/溶液生成结构的需求，也从我们的研究中受益。