Local Optical Activity in Achiral Two-Dimensional Gold Nanostructures
Local Optical Activity in Achiral Two-Dimensional Gold Nanostructures
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DOI：
10.1021/jp507168a
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发表时间：
2014-09-25
影响因子：
3.7
通讯作者：
Okamoto, Hiromi
中科院分区：
文献类型：
--
作者：
Hashiyada, Shun;Narushima, Tetsuya;Okamoto, Hiromi
自从巴斯德发现分子的手性（这意味着分子具有不可叠加的镜像）以来，材料的几何手性一直被认为是表现出结构起源的圆二色性（CD，定义为左右圆偏振光的差异吸收）的先决条件。在这里，我们报告了一个实验演示的非手性（非手性）矩形金纳米结构的纳米级局部CD活动。纳米结构样品的宏观CD光谱测量在整个测量波长范围内没有显示出任何CD活性，正如从矩形的非手性形状所预期的那样。相比之下，我们在单个矩形纳米结构中发现了局部正和负CD信号，其分布关于矩形的中心对称，在拐角处具有大的CD信号。结果表明，建立的旋光性的选择规则是不有效的局部微观测量。
Since Pasteur's discovery of molecular chirality, which means that the molecule has a nonsuperposable mirror image, the geometrical chirality of a material has been considered the prerequisite for exhibiting circular dichroism (CD, defined as the differential absorption of left and right circularly polarized light) of the structural origin. Here, we report an experimental demonstration of nanoscale local CD activities for achiral (nonchiral) rectangular gold nanostructures. Macroscopic CD spectral measurements of the nanostructure sample did not show any CD activity over the entire range of measured wavelengths, as expected from the achiral shape of the rectangle. In contrast, we found both locally positive and negative CD signals in a single rectangular nanostructure, whose distribution was symmetric about the center of the rectangle, with large CD signals at the corners. The results demonstrate that the established selection rule of optical activity is not valid for local microscopic measurements.