DMREF: Collaborative Research: Nanoscale Temperature Manipulation via Plasmonic Fano Interferences

热能，也被称为热，自然地从热的物体流向冷的物体。这种热流的一个后果是很难制造出具有局部“热点”的物体，即使对单个点施加热量也是如此。当触摸炉子上的热锅时，锅盖的顶部温度与加热的底部温度相差不大。当物体的尺寸接近几十到几百纳米，或者比人类头发小1000倍时，在一个小的空间区域内储存和保持热能变得更加具有挑战性。然而，在纳米尺度上控制热流和温度的能力对于从数据存储和化学反应的局部控制到通过离子通道刺激进行疾病治疗和疼痛管理的光热疗法等应用具有重要意义。在化学学部（CHE）和化学、生物工程、环境和运输系统学部（CBET）的设计材料变革和工程我们的未来（DMREF）项目的支持下，华盛顿大学的David J. Masiello教授，天普大学的Katherine A. Willets教授，和莱斯大学的斯蒂芬·林克教授正在开发方法，从理论上设计和实验上实现一种新型材料，这种材料能够将温度升高控制在纳米级空间区域。除了影响广泛的应用之外，该项目还通过三个研究小组之间的学生交换促进了学生和博士后研究人员的跨学科培训。研究人员和他们的学生正在一起设计等离子体纳米结构，利用范诺干涉来聚焦并将光辐射转换成精确的纳米级温度分布，这种温度分布可以从远场主动调节。他们正在开发计算机模拟来求解耦合麦克斯韦-热扩散方程，并利用它们来设计具有范诺干涉的新型等离子体纳米结构，该结构能够在低于衍射极限的尺寸下定位空间温度分布。然后在实验室中创建最佳候选者，并使用光学显微镜进行表征。衍射限制，单纳米粒子光热吸收光谱技术测量吸收的热功率以及在目标材料中引起的相关温度变化。荧光标记的茎环DNA结构用于实现纳米级温度剖面的超分辨率成像。然后将成像结果输入到下一代结构的设计中，提供迭代反馈，这对项目的成功至关重要。

Thermal energy, also known as heat, flows naturally from hot objects to cold objects. One consequence of this heat flow is that it is difficult to create objects with localized "hot spots," even when heat is applied to a single spot. When touching a hot pan on the stove, the temperature of the lid on top of the pan is not much different than the bottom where the heat is applied. Depositing and maintaining thermal energy in a small region of space becomes even more challenging as the object's size approaches the tens to hundreds of nanometers, or about 1,000 times smaller than a human hair. Yet, the ability to control heat flow and thus temperature at nanoscopic dimensions has important implications for applications ranging from data storage and the local control of chemical reactions to photothermal therapies for disease treatment and pain management through ion channel stimulation. With support from the Designing Materials to Revolutionize and Engineer our Future (DMREF) Program in the Division of Chemistry (CHE) and the Division of Chemical, Bioengineering, Environmental, and Transport Systems (CBET), Professor David J. Masiello from the University of Washington, Professor Katherine A. Willets from Temple University, and Professor Stephan Link from Rice University are developing methods to theoretically design and experimentally realize a new class of materials capable of controllably directing temperature increases to nanoscale regions of space. Beyond impacting a wide variety of applications, the project is also facilitating the interdisciplinary training of students and postdoctoral researchers through student exchange between the three research groups. Together, the researchers and their students are designing plasmonic nanostructures that exploit Fano interferences to focus and convert optical radiation into precise nanoscopic temperature profiles that are actively tunable from the far-field. They are developing computer simulations to solve the coupled Maxwell-heat diffusion equations and using them to design novel plasmonic nanostructures with Fano interferences that are capable of localizing spatial temperature profiles at dimensions below the diffraction limit. The best candidates are then created in the laboratory and characterized using optical microscopies. Diffraction-limited, single-nanoparticle photothermal absorption spectroscopy techniques measure the heat power absorbed as well as the associated temperature change induced in the target material. Fluorescently-labeled stem-loop DNA structures are used to achieve super-resolution imaging of the nanoscopic temperature profile. The imaging results are then input into the design of the next generation of structures, providing the iterative feedback that is critical to the project's success.