Nanocrystals (NCs) with identical components and sizes but different crystal structures could not be distinguished by conventional absorption and emission spectra. Herein, we find that circular dichroism (CD) spectroscopy can easily distinguish the CdSe nanoplatelets (NPLs) with different crystal structures of wurtzite (WZ) and zincblende (ZB) with the help of chiral l- or d-cysteine ligands. In particular, the CD signs of the first excitonic transitions in WZ and ZB NPLs capped by the same chiral cysteine are opposite. Theoretic calculation supports the viewpoint of different crystal structures and surfaces arrangements between WZ and ZB NPLs contributing to this significant phenomenon. The CD peaks appearing at the first excitonic transition band of WZ or ZB CdSe NPLs are clearly assigned to the different transition polarizations along 4p_(x,y,z),Se → 5s_Cd or 4p_(x,y),Se → 5s_Cd. This work not only provides a deep insight into the origin of the optical activity inside chiral semiconductor nanomaterials but also proposes the design principle of chiral semiconductor nanocrystals with high optic activity.

中文翻译：

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纤锌矿和Zincblende CdSe纳米片之间的不同激子圆二色性

具有相同成分和大小但晶体结构不同的纳米晶体（NC）不能通过常规吸收光谱和发射光谱来区分。在这里，我们发现圆二色谱（CD）可以借助手性l-或d轻松区分具有纤锌矿（WZ）和闪锌矿（ZB）不同晶体结构的CdSe纳米片（NPL）。-半胱氨酸配体。特别地，由相同的手性半胱氨酸封端的WZ和ZB NPL中的第一个激子跃迁的CD信号是相反的。理论计算支持了WZ和ZB NPL之间不同晶体结构和表面排列的观点，这是造成这一重大现象的原因。在WZ或ZB CdSe NPL的第一个激子跃迁带上出现的CD峰清楚地分配给沿4p _{（x，y，z），Se} →5s _Cd或4p _{（x，y），Se} →5s _Cd的不同跃迁极化。这项工作不仅可以深入了解手性半导体纳米材料内部光学活性的起源，而且可以提出具有高光学活性的手性半导体纳米晶体的设计原理。