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

热能，也称为热，自然地从热的物体流向冷的物体。这种热流的一个后果是，即使将热量施加到一个单独的点上，也很难创建具有局部“热点”的对象。当触摸炉子上的热锅时，锅盖上的温度与加热的底部没有太大差别。随着物体的大小接近几十到数百纳米，或者说大约1000倍于人类头发的尺寸，在很小的空间区域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从而控制温度的能力对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控制的光热疗法等应用具有重要意义。在化学系(CHE)和化学、生物工程、环境和交通系统系(CBET)设计材料革新和设计我们的未来(DMREF)计划的支持下，华盛顿大学的David J.Masiello教授、Temple大学的Katherine A.Willets教授和莱斯大学的Stephan Link教授正在开发方法，从理论上设计并实验实现一种能够将温度上升控制在空间纳米级区域的新型材料。除了影响广泛的应用，该项目还通过三个研究小组之间的学生交流，促进对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一起设计了等离子体纳米结构，这种结构利用法诺干涉来聚焦光辐射，并将其转化为精确的纳米温度分布，这些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的麦克斯韦-热扩散方程，并利用它们来设计具有Fano干扰的新型等离子体纳米结构，这些结构能够将空间温度分布局部化到低于衍射极限的维度。然后，在实验室中创造出最佳候选者，并使用光学显微镜对其进行表征。衍射受限的单纳米颗粒光热吸收光谱技术测量被吸收的热功率以及目标材料中引起的相关温度变化。荧光标记的茎环DNA结构被用来实现纳米温度分布的超分辨率成像。成像结果随后被输入到下一代结构的设计中，提供对项目成功至关重要的迭代反馈。

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.