Li Zehua, Kang Lei, Lord Robert W, Park Kyoungweon, Gillman Andrew, Vaia Richard A, Schaak Raymond E, Werner Douglas H, Knappenberger Kenneth L
Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States.
Department of Electrical Engineering and Center for Nanoscale Science, The Pennsylvania State University, University Park, Pennsylvania 16802, United States.
ACS Nanosci Au. 2021 Sep 21;2(1):32-39. doi: 10.1021/acsnanoscienceau.1c00014. eCollection 2022 Feb 16.
Throughout nature, simple rules explain complex phenomena, such as the selective interaction of chiral objects with circularly polarized light. Here, we demonstrate chiroptical signals from gold nanorods, which are seemingly achiral structures. Shape anisotropy due to atomic-level faceting and rounding at the tips of nanorods, which are free of chiral surface ligands, induces linear-to-circular polarization modulation during second harmonic generation. The intrinsic nanorod chiroptical response is increased by plasmon-resonant excitation, which preferentially amplifies circularly polarized harmonic signals. This structure-plasmon interplay is uniquely resolved by polarization-resolved second harmonic generation measurements. The material's second-order polarizability is the product of the structure-dependent lattice-normal susceptibility and local surface plasmon field vectors. Synthetically scalable plasmon-supporting nanorods that amplify small circular dichroism signals provide a simple, assembly-free platform for chiroptical transduction.
在整个自然界中，简单的规则可以解释复杂的现象，比如手性物体与圆偏振光的选择性相互作用。在此，我们展示了来自金纳米棒的手性光学信号，而金纳米棒看似是无手性的结构。由于纳米棒尖端的原子级刻面和圆化导致的形状各向异性，在没有手性表面配体的情况下，会在二次谐波产生过程中引起线性到圆偏振的调制。等离子体共振激发增强了纳米棒固有的手性光学响应，这种激发优先放大圆偏振谐波信号。这种结构与等离子体的相互作用通过偏振分辨二次谐波产生测量得以独特地解析。材料的二阶极化率是结构相关的晶格法向极化率与局部表面等离子体场矢量的乘积。能够放大小的圆二色性信号的可合成扩展的等离子体支持纳米棒，为手性光学转导提供了一个简单的、无需组装的平台。
