Department of Engineering , University of Cambridge , Trumpington Street , Cambridge CB2 1PZ , United Kingdom.
Department of Materials Science and Metallurgy , University of Cambridge , 27 Charles Babbage Road , Cambridge CB3 0FS , United Kingdom.
Nano Lett. 2018 Jun 13;18(6):3752-3758. doi: 10.1021/acs.nanolett.8b00955. Epub 2018 May 23.
Nanoparticles of some metals (Cu/Ag/Au) sustain oscillations of their electron cloud called localized surface plasmon resonances (LSPRs). These resonances can occur at optical frequencies and be driven by light, generating enhanced electric fields and spectacular photon scattering. However, current plasmonic metals are rare, expensive, and have a limited resonant frequency range. Recently, much attention has been focused on earth-abundant Al, but Al nanoparticles cannot resonate in the IR. The earth-abundant Mg nanoparticles reported here surmount this limitation. A colloidal synthesis forms hexagonal nanoplates, reflecting Mg's simple hexagonal lattice. The NPs form a thin self-limiting oxide layer that renders them stable suspended in 2-propanol solution for months and dry in air for at least two week. They sustain LSPRs observable in the far-field by optical scattering spectroscopy. Electron energy loss spectroscopy experiments and simulations reveal multiple size-dependent resonances with energies across the UV, visible, and IR. The symmetry of the modes and their interaction with the underlying substrate are studied using numerical methods. Colloidally synthesized Mg thus offers a route to inexpensive, stable nanoparticles with novel shapes and resonances spanning the entire UV-vis-NIR spectrum, making them a flexible addition to the nanoplasmonics toolbox.
一些金属（Cu/Ag/Au）的纳米颗粒会维持其电子云的振荡，这种振荡被称为局域表面等离激元共振（LSPR）。这些共振可以发生在光学频率，并可以通过光来驱动，从而产生增强的电场和引人注目的光子散射。然而，目前的等离子体金属较为稀有、昂贵，并且共振频率范围有限。最近，人们对丰富的 Al 元素给予了极大的关注，但 Al 纳米颗粒无法在红外区发生共振。本文报道的丰富的 Mg 纳米颗粒克服了这一限制。胶体合成形成了六方纳米板，反映了 Mg 的简单六方晶格。这些 NPs 形成了一个薄的自限制氧化层，使它们在 2-丙醇溶液中稳定悬浮数月，并在空气中干燥至少两周。它们通过光散射光谱在远场中维持可观察到的 LSPR。电子能量损失光谱实验和模拟揭示了多个尺寸相关的共振，其能量跨越了 UV、可见和 IR 区域。使用数值方法研究了模式的对称性及其与基底的相互作用。因此，胶体合成的 Mg 为具有新颖形状和共振的廉价、稳定的纳米颗粒提供了一条途径，这些共振横跨整个紫外可见近红外光谱，使它们成为纳米等离子体工具箱的一个灵活补充。
