Plasmonic metamaterials: enabling new routes for localized surface chemistry.

超材料是由周期性的纳米或微尺度构件组成的人工结构，通常由层状导体、半导体和介电屏障组成。在金属超材料中，局部电子共振，被称为等离子体共振，被定位在纳米结构附近。这些共振是高度可调谐的，可以用于各种应用，包括窄带滤光片，光伏元件和超灵敏分析设备。这项研究计划的长期目标是开发新的超材料，我们将利用这些超材料进行空间控制等离子体介导的化学反应和与过渡金属二硫族化合物（TMDs）的整合。总体目标在于了解在特定辐照条件下等离子体模式与其他分子或材料的基本相互作用。我们将开发具有特定形状和几何形状的新的二维元结构。具有线性或手性各向异性的结构将被创建和优化，以在可见和红外光谱范围内的线性或圆偏振光下响应。利用我们的纳米光子基础设施，结合加拿大光源的中红外光束线，将制造和表征从可见到红外范围的多重共振等离子体平台。等离子体介导的反应将使用这些结构进行研究。热载流子，电子或空穴，通过激发等离子体将用于研究反应，如重氮盐在金属表面的官能化或炔-叠氮化物环加成。热载流子的协同作用和可能的热效应将在温度控制条件下和不同辐照度的激发光源下进行研究。多化学图像化利用等离子体介导的化学将进行分形结构。这种结构表现出多个等离子体共振，每个等离子体共振都可以用特定的波长和极化选择性地激发，从而实现化学功能化的精确空间控制。我们将把tmd的激子性质与我们的超结构的表面等离子体共振结合起来。我们预期这种等离子体-激子混合材料将表现出增强的光学和传导特性。利用尖端增强光谱，我们期望测量增强的发光和二次谐波的产生。手性等离子体结构与激子波长相匹配的共振相结合，应能增强圆偏振光的发射。除了这个项目提供的基础知识外，新的混合特性和空间控制的等离子体分子模式将被用于下一代光子器件的概念，其性能和灵活性远远超过目前的水平。

Metamaterials are artificial structures composed of periodical nano- or micro-scale building blocks generally composed of layered conductors, semiconductors and dielectric barriers. In metallic metamaterials, local electronic resonances, known as plasmon resonances, are localized in the vicinity of the nanostructures. These resonances are highly tunable and can be exploited for a variety of applications including narrow-band optical filters, photovoltaic elements, and ultrasensitive analytical devices. The long-term objective of this proposed research program is to develop new metamaterials that we will exploit for spatially controlled plasmon-mediated chemical reactions and integration with transition metal dichalcogenides (TMDs). The overarching goal lies in understanding the fundamental interactions of plasmon modes with other molecules or materials under specific irradiation conditions. We will develop new 2D metastructures with specific shapes and geometries. Structures with linear or chiral anisotropies will be created and optimized to respond under linearly or circularly polarized light in both the visible and the infrared spectral ranges. Plasmonic platforms with multiple resonances spanning from the visible to the infrared range will be made and characterized using our nanophotonic infrastructure in conjunction with the mid-infrared beamline at the Canadian light source. Plasmon-mediated reactions will be investigated using these structures. Hot carriers, either electrons or holes, generated through the excitation of plasmons will be used to investigate reactions such as functionalization of diazonium salts on metal surfaces or alkyne-azide cycloadditions. The synergistic role of the hot carriers and probable thermal effects will be investigated under temperature-controlled conditions and under distinct irradiance of the excitation light source. Multichemical patterning using plasmon-mediated chemistry will be conducted on fractal structures. Such structures exhibit multiple plasmon resonances that can each be selectively excited with specific wavelengths and polarizations,  thus enabling precise spatial control of chemical functionalization. We will combine the excitonic properties of TMDs with surface plasmon resonances from our metastructures. We anticipate that such hybrid plasmon-exciton materials will exhibit enhanced optical and conduction properties. Using tip-enhanced spectroscopy, we expect to measure enhanced luminescence and second harmonic generation. The combination of chiral plasmonic structures with resonances that match the excitonic wavelength should yield enhanced emission of circularly polarized light. In addition to the fundamental knowledge provided by this program, the new hybrid properties and spatially controlled molecular patterning enabled by plasmon will be exploited for the conception of the next generation of photonic devices with performance and flexibility well beyond the state of the art.