Collaborative Research: Experimental and Computational Study of the Instabilities, Transport, and Self Assembly of Nanoscale Metallic Thin Films and Nanostructures

该项目主要研究液态金属薄膜和其他结构在纳米尺度上的稳定性。纳秒脉冲激光熔化可以产生空间相关的纳米粒子组合，主要目的是探索驱动这一过程的基本机制。本项目的显著特点是采用协同方法，包括基于连续流体力学的建模、针对性实验和配套的分子动力学模拟。中心目标是利用细致彻底的实验调查和纳米级液态金属薄膜的最先进的理论和计算模型来解决几个基本的科学问题，例如：如何开发合理简单但预测的模型来描述纳米级液态金属的相关力？多尺度建模（分子动力学和连续流体动力学）方法在多大程度上可以用来跨越实验长度尺度？如何利用熔融液态金属的相互作用来促进纳米尺度上的自组装和自组织？为了解决这些问题，我们将研究石墨衬底上的铂-钌二元金属体系。该系统经过精心选择，因此可以进行互补连续流体动力学和分子动力学模拟，以了解相关的界面势以及相互竞争的界面混合和凝固动力学。薄膜和其他几何形状将被合成，以研究导致纳米颗粒组装的不稳定性相关的固-液-气相互作用，研究凝固动力学对多功能纳米颗粒合成的影响，并探索作为定向组装途径的强加热不稳定性。实验工作将辅以理论和计算工作，包括多维非线性模拟，包括液固相互作用势、热和相变效应、扩散混合以及其他效应。该项目的成功完成将使人们对金属纳米结构的基本液相组装的理解取得重大进展。纳米粒子的自定向组装具有重要意义的一个应用例子是太阳能电池装置的设计，其中已知金属粒子的大小和分布与等离子体激元与入射能量的耦合有关，具有提高产量的巨大潜力。更一般地说，纳米组装在许多领域都很重要，从与DNA测序相关的能源。该项目还包括开发互补的连续和分子动力学模拟，这将允许相关空间和时间尺度的桥接，提供关于纳米尺度连续建模的局限性和适用性的一般见解。该项目将包括来自多个STEM学科的研究生和本科生，并将与阿根廷的一个研究小组进行国际合作。

1235710/1235651Kondic/RackThe project focuses on stability of liquid metal films and other structures on nanoscale. Nanosecond pulsed laser melting can produce spatially correlated nanoparticle assemblies, and the main goal is to explore the fundamental mechanisms driving this process. The distinguishing feature of this project is synergetic approach including modeling based on continuum fluid mechanics, targeted experiments, and supporting molecular dynamics simulations. The central goal is to leverage careful and thorough experimental investigations and state of the art theoretical and computational modeling of nanoscale liquid metal films to address several basic scientific questions such as: How to develop reasonably simple but predictive models to describe the forces relevant to liquid metals on nanoscale? To which degree can multi-scale modeling (molecular dynamics and continuum fluid dynamics) approaches be used to bridge experimental length scales? How to use the interactions characterizing molten liquid metals to promote self-assembly and self-organization at the nanoscale? To address these questions, the platinum-ruthenium binary metal system on graphite substrates will be investigated. The system was carefully chosen so complementary continuum fluid dynamics and molecular dynamics simulations can be performed to understand the relevant interface potentials as well as competing interfacial mixing and solidification dynamics. Thin films and other geometries will be synthesized to investigate solid-liquid-vapor interactions relevant to instabilities leading to nanoparticle assemblies, study the effects that the solidification dynamics has on synthesis of multi-functional nano particles, and to explore imposed thermal instabilities as a route to directed assembly. Experimental efforts will be complemented by theoretical and computational work, involving multi-dimensional nonlinear simulations including liquid-solid interaction potentials, thermal and phase change effects, and diffusive mixing, among other effects. Successful completion of the project will allow for significant advancement in under- standing of fundamental liquid phase assembly of metallic nanostructures. One example of an application where self- and directed assembly of nano particles is of significant importance is the design of solar cell devices where it is known that the size and distribution of metallic particles is related to plasmon coupling to incident energy, with the huge potential in increasing the yield. More generally, nano-assembly is of importance in a variety of fields, ranging from energy related to DNA sequencing. The project also includes development of complementary continuous and molecular dynamics simulations which will allow for bridging of relevant spatial and temporal scales, providing general insight regarding limits and applicability of continuum modeling on nanoscale. The project will include graduate and undergraduate students from multiple STEM disciplines and will involve international collaboration with a research group in Argentina.