Opt Express. 2021 Mar 15;29(6):8087-8097. doi: 10.1364/OE.419614.
Induced circular dichroism (ICD) has been used to detect biomolecular conformations through the coupling between chiral molecules and achiral metal nanostructures with the localized surface plasmon (LSP). However, this ICD is always weak and cannot be dynamically adjusted. Here, we put dielectric and graphene nanostructures on a metal-substrate for restricting more light energies and obtaining dynamic adjustable performance. A composite nanostructure array composed of achiral silicon-nanorods on a metal-substrate and graphene-ribbons (ASMG) is theoretically investigated. Two strong ICD signals appear in the THz region. Near-field magnetic distributions of ASMG reveal that the two strong ICD signals are mainly due to the surface plasmon resonances (SPPs) on the metal-substrate and LSP in the graphene nanostructures, respectively. The ICD signals strongly depend on the geometric parameters of ASMG and are dynamically adjusted by just changing the Fermi levels of graphene-ribbons. In addition, left-handed ASMG and right-handed ASMG can be used to identify the chiral molecular solutions with different chiralities. The maximum enhancement factor of the chiral molecular solutions could reach up to 3500 times in the THz region. These results can help to design dynamically adjustable THz chiral sensors and promote their application in biological monitoring and asymmetric catalysis.
圆二色性（ICD）已被用于通过手性分子与具有局域表面等离子体（LSP）的非手性金属纳米结构之间的耦合来检测生物分子构象。然而，这种 ICD 通常很弱，并且不能动态调节。在这里，我们在金属衬底上放置介电和石墨烯纳米结构，以限制更多的光能并获得动态可调性能。理论上研究了由金属衬底上的非手性硅纳米棒和石墨烯带（ASMG）组成的复合纳米结构阵列。在太赫兹区域出现了两个强 ICD 信号。ASMG 的近场磁场分布表明，这两个强 ICD 信号主要归因于金属衬底上的表面等离子体共振（SPP）和石墨烯纳米结构中的 LSP。ICD 信号强烈依赖于 ASMG 的几何参数，并且通过仅改变石墨烯带的费米能级就可以动态调节。此外，左手 ASMG 和右手 ASMG 可用于识别具有不同手性的手性分子溶液。在手性分子溶液的太赫兹区域，最大增强因子可达 3500 倍。这些结果有助于设计动态可调谐太赫兹手性传感器，并促进其在手性生物监测和不对称催化中的应用。
