纳米体系手征光学性质研究

We conduct research on the chiral optical properties of nanostructures combining with the recent experimental results of such variable and tunable systems. We study the different optical response to the light with different polarization (circular dichroism,etc) of the hybrid nanostructures made of quantum dots, metallic nanoparticles, chiral molecules, etc. We try to reveal the mechanisms of chirality at nanoscale. We investigate the interplay of several effects (quantum confinement effect, geometry and symmetry effect, near field effect,etc); We explore the relation between spatial configuration and charility in the composite nanostructures; We study the interaction between the single particle excitations (excitons) and collective excitations (plasmons), paying special attention to their roles in the chiral optical properties; We analysis the relative roles of charility of different mechanism and origin. With the help of the tunability of hybrid nanostructures, we put forward effective methods for generation and modulation of chirality in the systems in a wide range (including UV, visible light and IR regimes). We construct theoretical models based on the classical electrodynamics and quantum density matrix theory, and develop effective analytical and numerical methods, to analyze, explain and understand the relevant experiments and propose design principle for new experiments. This study will deepen our understanding of the basic physical principle of nanostructures, in particular the understanding of chirality at nanoscale, which has important applications in biomedicines.

结合多样、可调的纳米体系实验新成果,我们开展纳米体系手征光学性质的研究。该项目将研究由量子点,金属纳米颗粒,手征分子等作为基本基石构成的复合纳米体系对不同偏振光的不同响应（圆二色谱等）,揭示纳米尺度手征性产生的机制；考察体系中多种效应(受限效应,几何对称性效应,近场效应等)的综合作用;探究复合纳米体系空间构型与体系手征性的关系；研究体系个体激发（激子）与集体激发（等离激元）的相互作用，特别关注其在体系手征光学性质中的表现；分析不同起源、机制的手性的相对作用；提出利用复合纳米体系可调性实现广泛区间（紫外、可见光、红外）手征性并对其调控的有效手段；建立基于经典电磁场理论和量子密度矩阵的理论模型，发展有效解析和数值计算方法，分析、解释、理解相关实验，并提出新实验设计原理方案。该项目研究将深化人们对纳米体系基本物理规律，特别是纳米尺度手征性的认识，它在生物医学等方面有重要作用。

手征性在自然界广泛存在，在诸多领域有重要应用。纳米体系结构的可调控性为手征性的研究提供了更广阔的平台。我们在复合纳米体系（手征）光学性质方面开展了有成效研究工作,取得了有意义的研究成果。我们系统研究了由(手性)分子、DNA Origami、（核壳）纳米颗粒构成的复合体系手性光学响应，利用复合微纳结构和外磁场的调节理解纳米尺度手性光学响应的新特征。研究工作发现：由手性分子Cysteine链接金纳米棒形成不同空间构型结构的诱导手性导致的圆二色（CD）谱，热点（hotspot） 局域场增强和反作用的竞争使肩并肩构型下的CD强于头对头构型下的CD；DNA Origami和金属纳米复合体系的各向异性光学手性；Au@Ag核壳纳米颗粒和Cysteine分子复合结构的带间跃迁相关的诱导光学手性；外磁场和空间构型调控的新颖手性光学响应。我们的研究工作揭示了纳米尺度手性响应的物理机制，指出了诱导手性、结构手性的特点、特征，提出了空间构型和外（磁）场调控光学手征响应的方案与手段。我们发展了复合纳米体系手性光学理论建模、有效解析和数值计算方法，和实验工作紧密结合，分析、解释、理解了相关实验，深化了纳米尺度手性光学响应机理的认识。项目执行期间在包括Nano Lett. [IF 13.78]，Advanced Materials [IF 18.96]，ACS Nano. [IF 13.33]，Angew. Chem. Int. Ed. [IF=11.71]，J. Am. Chem. Soc. [IF 12.11] 等的SCI期刊发表17篇论文（均标注本项目资助）。