The optoelectronic properties of asymmetric metal nanostructures are of current interest for applications in photonics, sensing, and catalysis. Here, we break the symmetry of the localized surface plasmon resonance of gold nanorods by selective overgrowth of a single tip via a high-yield (${\gt}{80}\%$) wet-chemical method. While optical spectroscopy exhibits a bathochromic shift of the nanoparticle plasmon resonance, cathodoluminescence and electron energy loss spectroscopy measurements reveal a breaking of the symmetry of the associated localized surface plasmon resonance mode, which results in the subwavelength concentration of electromagnetic energy. The simple, one-step postsynthetic modification allows control of nanoparticle structural parameters, and we demonstrate how the asymmetric energy redistribution leads to increases in the surface-enhanced Raman scattering of a model analyte attached to the surface of the nanostructures. The spatial localization of energy in these nanostructures may find applications in nanofocusing, nanoimaging, and light harvesting.

中文翻译：

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通过金纳米棒的不对称生长打破等离子体对称性

对于光子学，传感和催化中的应用，不对称金属纳米结构的光电性质是当前感兴趣的。在这里，我们通过高收益率（$ {\ gt} {80} \％$）单个尖端的选择性过度生长，打破了金纳米棒的局部表面等离振子共振的对称性。）湿化学法。虽然光学光谱显示出纳米粒子等离子体共振的红移，但是阴极发光和电子能量损失光谱测量显示相关的局部表面等离子体共振模式的对称性的破坏，这导致亚波长的电磁能集中。简单的一步合成后修饰可以控制纳米粒子的结构参数，并且我们证明了不对称能量的重新分布如何导致附着在纳米结构表面的模型分析物的表面增强拉曼散射增加。这些纳米结构中能量的空间定位可能会在纳米聚焦，纳米成像和光收集中找到应用。