Geballe Laboratory for Advanced Materials, Stanford University , Stanford, California 94305, United States.
Nano Lett. 2011 Oct 12;11(10):4265-9. doi: 10.1021/nl202256k. Epub 2011 Sep 15.
We perform spectrally resolved cathodoluminescence (CL) imaging nanoscopy using a 30 keV electron beam to identify the resonant modes of an ultrathin (20 nm), laterally tapered plasmonic Ag nanostrip antenna. We resolve with deep-subwavelength resolution four antenna resonances (resonance orders m = 2-5) that are ascribed to surface plasmon polariton standing waves that are confined on the strip. We map the local density of states on the strip surface and show that it has contributions from symmetric and antisymmetric surface plasmon polariton modes, each with a very different mode index. This work illustrates the power of CL experiments that can visualize hidden modes that for symmetry reasons have been elusive in optical light scattering experiments.
我们使用 30keV 电子束进行光谱分辨的阴极发光（CL）成像纳米显微镜，以识别超薄（20nm）、横向锥形等离子体 Ag 纳米条天线的共振模式。我们以深亚波长分辨率分辨出四个天线共振（共振阶数 m=2-5），这归因于限制在条带上的表面等离激元极化激元驻波。我们绘制了条带表面上的局域态密度，并表明它有来自对称和反对称表面等离激元极化激元模式的贡献，每个模式都具有非常不同的模式指数。这项工作说明了 CL 实验的强大功能，可以可视化由于对称性原因而在光学散射实验中难以捉摸的隐藏模式。
