Lu Xianmao, Rycenga Matthew, Skrabalak Sara E, Wiley Benjamin, Xia Younan
Department of Biomedical Engineering, Washington University, St. Louis, Missouri 63130, USA.
Annu Rev Phys Chem. 2009;60:167-92. doi: 10.1146/annurev.physchem.040808.090434.
Under the irradiation of light, the free electrons in a plasmonic nanoparticle are driven by the alternating electric field to collectively oscillate at a resonant frequency in a phenomenon known as surface plasmon resonance. Both calculations and measurements have shown that the frequency and amplitude of the resonance are sensitive to particle shape, which determines how the free electrons are polarized and distributed on the surface. As a result, controlling the shape of a plasmonic nanoparticle represents the most powerful means of tailoring and fine-tuning its optical resonance properties. In a solution-phase synthesis, the shape displayed by a nanoparticle is determined by the crystalline structure of the initial seed produced and the interaction of different seed facets with capping agents. Using polyol synthesis as a typical example, we illustrate how oxidative etching and kinetic control can be employed to manipulate the shapes and optical responses of plasmonic nanoparticles made of either Ag or Pd. We conclude by highlighting a few fundamental studies and applications enabled by plasmonic nanoparticles having well-defined and controllable shapes.
在光的照射下，等离子体纳米颗粒中的自由电子在交变电场的驱动下，以共振频率集体振荡，这种现象称为表面等离子体共振。计算和测量都表明，共振的频率和幅度对颗粒形状敏感，颗粒形状决定了自由电子在表面的极化和分布方式。因此，控制等离子体纳米颗粒的形状是定制和微调其光学共振特性的最有效手段。在溶液相合成中，纳米颗粒呈现的形状由所产生的初始晶种的晶体结构以及不同晶种晶面与封端剂的相互作用决定。以多元醇合成为典型例子，我们说明了如何利用氧化蚀刻和动力学控制来操纵由银或钯制成的等离子体纳米颗粒的形状和光学响应。我们通过强调一些由形状明确且可控的等离子体纳米颗粒实现的基础研究和应用来进行总结。
