Salmon Andrew R, Kleemann Marie-Elena, Huang Junyang, Deacon William M, Carnegie Cloudy, Kamp Marlous, de Nijs Bart, Demetriadou Angela, Baumberg Jeremy J
Nanophotonics Centre, Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE, United Kingdom.
School of Physics and Astronomy, University of Birmingham, Birmingham B15 2TT, United Kingdom.
ACS Nano. 2020 Apr 28;14(4):4982-4987. doi: 10.1021/acsnano.0c01213. Epub 2020 Apr 1.
The properties of nanoplasmonic structures depend strongly on their geometry, creating the need for high-precision control and characterization. Here, by exploiting the low activation energy of gold atoms on nanoparticle surfaces, we show how laser irradiation reshapes nanoparticle dimers. Time-course dark-field microspectroscopy allows this process to be studied in detail for individual nanostructures. Three regimes are identified: facet growth, formation of a conductive bridge between particles, and bridge growth. Electromagnetic simulations confirm the growth dynamics and allow measurement of bridge diameter, found to be highly reproducible and also self-limiting. Correlations in spectral resonances for the initial and final states give insight into the energy barriers for bridge growth. Dark-field microscopy shows that coalescence of multiple gaps in nanoparticle clusters can be digitally triggered, with each gap closing after discrete increases in irradiation power. Such control is important for light-induced nanowire formation or trimming of electronic and optoelectronic devices.
纳米等离子体结构的性质强烈依赖于其几何形状，因此需要高精度的控制和表征。在这里，通过利用金原子在纳米颗粒表面的低活化能，我们展示了激光辐照如何重塑纳米颗粒二聚体。时间分辨暗场显微光谱法使我们能够对单个纳米结构的这一过程进行详细研究。确定了三个阶段：晶面生长、颗粒间形成导电桥以及桥的生长。电磁模拟证实了生长动力学，并能够测量桥的直径，发现其具有高度的可重复性且具有自限性。初始态和终态光谱共振的相关性有助于深入了解桥生长的能垒。暗场显微镜显示，纳米颗粒簇中多个间隙的合并可以通过数字方式触发，每次间隙在辐照功率离散增加后闭合。这种控制对于光诱导纳米线的形成或电子和光电器件的修整非常重要。
