Size and Morphology Dependence of the Hamaker Constant for Noble Metal Nanoparticles

该奖项由2009年《美国复苏和再投资法案》（公共法111-5）资助。技术总结：将使用应用于纳米颗粒沉淀动力学的时间分辨光学吸收光谱，从理论和实验上研究金和银纳米颗粒的Hamaker常数的形态和尺寸依赖性。该项目的目标是从实验和理论上证明，Hamaker常数是贵金属纳米颗粒的尺寸和形态依赖性。吸收光谱法将用于监测贵金属纳米颗粒沉淀的动力学，作为含有它们的溶液的盐浓度的函数。沉淀动力学将用于计算不同尺寸和形态的纳米颗粒的Hamaker常数。该项目的主要假设是，小的贵金属纳米颗粒的Hamaker常数是尺寸和形态相关的，这是贵金属这些常数的文献值中报告的偏差的原因。Hamaker常数的尺寸依赖性源于贵金属纳米颗粒中表面等离子体共振的尺寸效应，这可能对Hamaker常数有显着贡献。该项目的结果将建立波动耗散力和集体电子激发之间的基本关系，称为金属纳米颗粒中的表面等离子体共振，并将促进我们模拟纳米级相互作用和模拟金属纳米颗粒自组装的能力。非技术性总结：金属纳米粒子是自下而上自组装工艺的主要组成部分，在生物化学传感器、亚波长光波导和纳米光学等领域发挥着越来越重要的作用。了解金属纳米颗粒之间的作用力是精细和精确控制自组装过程的先决条件。该项目将研究溶液中纳米粒子之间的作用力，并更好地控制自组装过程。这项研究的结果将对纳米技术在纳米粒子自组装领域的发展产生深远的影响，并将产生重大的教育影响。了解金属纳米颗粒之间的相互作用潜力对于开发新的高效纳米纤维技术至关重要。纳米技术和纳米纤维的快速发展需要对本科生和研究生进行充分的培训，以跟上新的趋势，并满足这些不断扩大的研究和经济部门日益增长的需求。本科生和研究生需要以足够的背景和培训来应对这种扩张的挑战。这个项目将联合收割机研究和教育计划，适当准备研究生和本科生在纳米技术的这种研究。

This Award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).TECHNICAL SUMMARY:The morphology and size dependence of the Hamaker constants for gold and silver nanoparticles will be investigated theoretically and experimentally using time resolved optical absorption spectroscopy applied to the precipitation dynamics of the nanoparticles. The goal of this project is to show experimentally and theoretically that the Hamaker constant is size and morphology dependent for noble metal nanoparticles. Absorption spectroscopy will be used to monitor the dynamics of the precipitation of noble nanoparticles as a function of the salt concentration of the solution containing them. The kinetics of precipitation will be used to calculate the Hamaker constant of the nanoparticles of different size and morphology. The main hypothesis of the project is that the Hamaker constant for small noble nanoparticles is size and morphology dependent and this is the reason for the deviations in the reported literature values of these constants for noble metals. The size dependence of the Hamaker constant stems from the size effect for the Surface Plasmon Resonance in noble metal nanoparticles, which might contribute significantly to the Hamaker constant. The results of this project will establish a fundamental relation between fluctuation-dissipation forces and collective electronic excitations known as Surface Plasmon Resonances in metal nanoparticles and will facilitate our capability to simulate interaction on the nanoscale and to model the self-assembly of metal nanoparticles. NON-TECHNICAL SUMMARY: Metal nanoparticles are the major components of the bottom-up self-assembly fabrication process and play an increasingly important role in the development of biochemical sensors, optical subwavelength waveguides and nano-optics. Understanding the forces between metal nanoparticles is a precondition for the fine and precise control of the self-assembly process. This project will investigate the forces acting between nanoparticles in solution and lead to better control over the self assembly process. The results of this study will have a profound effect on the development of nanotechnology in the area of self-assembly of nanoparticles and will have a significant educational influence. Understanding the interaction potential between metal nanoparticles is essential for the development of new and efficient nanofabrication technologies. The rapid development of nanotechnology and nanofabrication requires adequate training of undergraduate and graduate students in order to keep up with the new trends and to match the growing needs of these expanding sectors of research and economy. Undergraduate and graduate students need to meet the challenges of this expansion with sufficient background and training. This project will combine research and education programs to properly prepare graduate and undergraduate students for this kind of research in nanotechnology.