Baimuratov Anvar S, Rukhlenko Ivan D, Noskov Roman E, Ginzburg Pavel, Gun'ko Yurii K, Baranov Alexander V, Fedorov Anatoly V
ITMO University, 197101 Saint Petersburg, Russia.
Monash University, Clayton Campus, Victoria 3800, Australia.
Sci Rep. 2015 Oct 1;5:14712. doi: 10.1038/srep14712.
For centuries mankind has been modifying the optical properties of materials: first, by elaborating the geometry and composition of structures made of materials found in nature, later by structuring the existing materials at a scale smaller than the operating wavelength. Here we suggest an original approach to introduce optical activity in nanostructured materials, by theoretically demonstrating that conventional achiral semiconducting nanocrystals become optically active in the presence of screw dislocations, which can naturally develop during the nanocrystal growth. We show the new properties to emerge due to the dislocation-induced distortion of the crystal lattice and the associated alteration of the nanocrystal's electronic subsystem, which essentially modifies its interaction with external optical fields. The g-factors of intraband transitions in our nanocrystals are found comparable with dissymmetry factors of chiral plasmonic complexes, and exceeding the typical g-factors of chiral molecules by a factor of 1000. Optically active semiconducting nanocrystals-with chiral properties controllable by the nanocrystal dimensions, morphology, composition and blending ratio-will greatly benefit chemistry, biology and medicine by advancing enantiomeric recognition, sensing and resolution of chiral molecules.
几个世纪以来，人类一直在改变材料的光学特性：最初是通过精心设计由天然材料制成的结构的几何形状和成分，后来是通过在小于工作波长的尺度上对现有材料进行结构化处理。在此，我们提出一种在纳米结构材料中引入光学活性的原创方法，通过理论证明传统的非手性半导体纳米晶体在存在螺旋位错时会变得具有光学活性，而螺旋位错在纳米晶体生长过程中会自然形成。我们表明，由于位错引起的晶格畸变以及纳米晶体电子子系统的相关改变，新特性得以出现，这从本质上改变了其与外部光场的相互作用。我们发现纳米晶体带内跃迁的g因子与手性等离子体复合物的不对称因子相当，并且比手性分子的典型g因子高出1000倍。具有可通过纳米晶体尺寸、形态、成分和混合比例控制的手性特性的光学活性半导体纳米晶体，将通过推进手性分子的对映体识别、传感和拆分，极大地造福于化学、生物学和医学。
