Abstract Recent developments in the application of plasmonic nanoparticles have showcased the importance of understanding in detail their plasmonic resonances at the single-particle level. These resonances can be excited and probed through various methods, which can be grouped in four categories, depending on whether excitation and detection involve electrons (electron energy loss spectroscopy), photons (e.g., dark-field microscopy), or both (cathodoluminescence and photon-induced near-field electron microscopy). While both photon-based and electron-based methods have made great strides toward deepening our understanding of known plasmonic properties and discovering new ones, they have in general progressed in parallel, without much cross-pollination. This evolution can be primarily attributed to the different theoretical approaches driving these techniques, mainly dictated by the inherent different nature of electrons and photons. The discrepancies that still exist among them have hampered the development of a holistic approach to the characterization of plasmonic materials. In this review therefore, we aim to briefly present those electron-based and photon-based methods fundamental to the study of plasmonic properties at the single-particle level, with an eye to new behaviors involving multipolar, propagating, and bulk modes coexisting in colloidal nanostructures. By exploring the key fundamental discoveries in nanoparticle plasmonics achieved with these techniques, herein we assess how integrating this information could encourage the creation of a unified understanding of the various phenomena occurring in individual nanoparticles, which would benefit the plasmonics and electron microscopy communities alike.

中文翻译：

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多极和体模式：通过电子和光子技术的进步单粒子等离子体的基础

摘要 等离子体纳米粒子应用的最新进展表明，在单粒子水平上详细了解它们的等离子体共振的重要性。这些共振可以通过各种方法激发和探测，这些方法可以分为四类，具体取决于激发和检测是否涉及电子（电子能量损失光谱）、光子（例如，暗场显微镜）或两者（阴极发光和光子-诱导近场电子显微镜）。虽然基于光子和基于电子的方法在加深我们对已知等离子体特性的理解和发现新特性方面取得了长足的进步，但它们通常是并行发展的，没有太多的异花授粉。这种演变主要归因于驱动这些技术的不同理论方法，主要是由电子和光子固有的不同性质决定的。它们之间仍然存在的差异阻碍了等离子体材料表征的整体方法的发展。因此，在这篇综述中，我们旨在简要介绍那些在单粒子水平上研究等离子体特性的基础的基于电子和基于光子的方法，着眼于涉及多极、传播和体模式共存于胶体的新行为。纳米结构。通过探索使用这些技术实现的纳米粒子等离子体的关键基础发现，