Plasmonic metamaterials: enabling new routes for localized surface chemistry.

超材料是由周期性纳米或微米尺度构建块组成的人工结构，通常由层状导体、半导体和电介质阻挡层组成。在金属超材料中，被称为等离子体共振的局部电子共振位于纳米结构附近。这些共振是高度可调的，可以用于各种应用，包括窄带光学滤波器，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，我们将利用这些材料进行空间控制等离子体介导的化学反应，并与过渡金属二硫属化物（TMD）集成。总体目标在于理解在特定照射条件下等离子体激元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2D亚结构。将创建和优化具有线性或手性各向异性的结构，以在可见光和红外光谱范围内的线性或圆偏振光下响应。具有从可见光到红外范围的多个共振的等离子体平台将使用我们的纳米光子基础设施与加拿大光源的中红外光束线相结合进行制作和表征。 等离子体介导的反应将使用这些结构进行研究。通过等离子体激元激发产生的热载流子，无论是电子还是空穴，将用于研究反应，如金属表面重氮盐的官能化或炔-叠氮环加成。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的激发光源的辐照度下进行研究。将在分形结构上进行使用等离子体介导的化学的多化学图案化。这样的结构表现出多个等离子体共振，每个等离子体共振可以用特定的波长和偏振选择性地激发，从而使得能够精确地空间控制化学官能化。 我们将结合联合收割机的激子性能的TMD与表面等离子体共振从我们的亚结构。我们预计，这种混合等离子激元材料将表现出增强的光学和导电性能。利用针尖增强光谱，我们期望测量增强发光和二次谐波产生。手性等离子体结构与匹配激子波长的共振的组合应产生圆偏振光的增强发射。除了该计划提供的基础知识外，新的混合特性和由等离子体激元实现的空间控制分子图案化将被用于下一代光子器件的概念，其性能和灵活性远远超出了现有技术。

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.