Charging and Heating Dynamics of Nanoparticles in Nonthermal Plasmas

提案题目：非热等离子体中纳米粒子的充电和加热动力学首席研究员：Kortshagen， Uwe R.机构：明尼苏达大学-双城提案号：CBET-0903842自20世纪80年代以来，“尘埃”或“复杂”等离子体的各个方面一直在继续激发等离子体界的兴趣。在微电子设备的制造过程中，纳米颗粒的形成产生了有害的影响，这引发了人们的第一波兴趣。与此同时，强耦合等离子体中令人兴奋的新物理现象的发现，催生了复杂等离子体研究领域的蓬勃发展。最近出现了一个新的关注焦点：利用反应性尘埃等离子体作为纳米粒子的可控来源。这些纳米颗粒具有有趣的物理和化学性质，使它们具有新的应用前景。然而，即使经过十多年的研究，这种“纳米尘埃”等离子体的一些最基本的物理过程仍然知之甚少。此外，由于制备表征良好的“纳米尘埃”等离子体实验系统的困难，我们的大多数知识都是基于缺乏实验验证的模型。本研究的总体目标是研究纳米粒子在高度确定的、具有良好特征的低温等离子体环境中充电和加热的基本动力学。为了实现这一目标，将使用一种独特的工艺来合成高度单分散的发光纳米晶体，其直径范围在3-20纳米之间；这些粒子将被注入精心设计和表征的测试等离子体中。对于纳米粒子的充电问题，实验将对尺寸控制的纳米粒子进行测试，以测试是否需要对小纳米粒子使用轨道运动限制理论或考虑碰撞效应的理论。另一个高风险/高回报的实验将首次尝试测量浸泡在等离子体中的纳米粒子的电荷分布。这些实验结果将为后续的模型研究提供新的信息。对于纳米粒子在等离子体中的加热，将使用“纳米粒子温度计”进行一系列首次实验，以研究等离子体中单分散纳米粒子的平均温度，并获得其温度分布函数的信息。一组实验将利用纳米粒子的光致发光的温度依赖性来获得有关粒子温度的信息。另一组实验将利用纳米颗粒的微观结构来确定颗粒温度是否达到或超过颗粒温度？结晶温度。这些实验结果将与颗粒加热的数值模型进行比较。这项研究具有广泛的影响。在技术方面，它将为利用等离子体作为用于纳米技术的功能性纳米粒子的来源建立科学基础。它还将成为若干教育和外联活动的跳板。这些措施包括通过当地公立学区开展K-12教育；本科生参与研究；在高度跨学科的研究环境中培养研究生和本科生；新型跨学科研究生课程的教学鼓励女性和代表性不足的群体更多地参与我们的研究生研究项目；积极参与工业活动。

Proposal Title: Charging and Heating Dynamics of Nanoparticles in Nonthermal PlasmasPrincipal Investigator: Kortshagen, Uwe R. Institution: University of Minnesota-Twin Cities Proposal No: CBET-0903842 Various aspects of "dusty" or "complex" plasmas have continued to excite the plasma com-munity since the 1980s. The first wave of interest was sparked by the detrimental effects of the formation of nanoparticles during the manufacture of microelectronic devices. In parallel, the discovery of exciting new physical phenomena in strongly coupled plasmas gave birth to the booming field of complex plasma studies. Recently a new focus of attention has emerged: Using reactive dusty plasmas as controllable sources of nanoparticles. These nanoparticles have interesting physical and chemical properties that make them promising for novel applications. However, even after more than a decade of study, some of the most basic physical processes of such "nanodusty" plasmas are still poorly understood. Moreover, due to the difficulties of preparing well-characterized experimental systems of "nanodusty" plasmas, most of our knowledge is based on models that lack experimental verification.The overall objective of this research is to study the fundamental dynamics of nanoparticle charging and heating in highly defined, well-characterized low temperature plasma environments. To achieve this objective, a unique process to synthesize highly monodisperse, luminescent nanocrystals with well-defined diameters in the range of 3-20 nm will be used; these particles will be injected into carefully designed and characterized test plasmas. For the nanoparticle charging problem, experiments will be performed with size-controlled nanoparticles to test whether the orbital-motion-limited theory or a theory accounting for collisional effects needs to be used for small nanoparticles. Another high-risk/high-reward experiment will attempt to measure, for the first time, the charge distribution of nanoparticles immersed in a plasma. Results of these experiments will provide new information for accompanying modeling studies. For nanoparticle heating in plasmas, a set of first-ever experiments will be performed using "nanoparticle thermometers" to study the average temperature of monodisperse nanoparticles in plasmas as well as to gain information about their temperature distribution function. One set of experiments will exploit the temperature-dependence of the photoluminescence of nanoparticles to gain information about particle temperatures. Another set of experiments will use the nanoparticles' microstructure to determine whether the particle temperature reached or exceeded the particles? crystallization temperature. Results of these experiments will be compared to numerical models for particle heating.This research has a wide range of broader impacts. On the technical side, it will build the scientific foundation for the use of plasmas as sources of functional nanoparticles for uses in nanotechnology. It will also serve as a springboard for a number of education and outreach activities. These include K-12 outreach through local public school districts; involvement of undergraduates in research; training of graduate and undergraduate students in a highly interdisciplinary research environment; teaching of new interdisciplinary graduate courses; fostering greater involvement of women and underrepresented groups in our graduate research programs; and active engagement with industry.