Wu Zhen, Zhang Yuanyuan, Hu Rongrong, Jiang Meizhen, Liang Pan, Yang Qing, Deng Li, Jia Tianqing, Sun Zhenrong, Feng Donghai
State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200241, China.
College of Sciences, Shanghai Institute of Technology, Shanghai 201418, China.
J Phys Chem Lett. 2021 Mar 4;12(8):2126-2132. doi: 10.1021/acs.jpclett.0c03669. Epub 2021 Feb 24.
Electron spin dynamics in CdSe quantum dots with hole acceptors are investigated by time-resolved ellipticity spectroscopy. Two types of hole acceptors, Li[EtBH] and 1-octanethiol, result in distinctly different electron spin dynamics. The differences include electron factors, spin dephasing/relaxation times, and mechanisms. In CdSe quantum dots with Li[EtBH], the electron spin dephasing and relaxation are dominated by electron-nuclear hyperfine interactions in zero and weak magnetic fields. In contrast, hyperfine interactions, electron carrier lifetimes, and exchange interactions between electrons and holes or surface dangling bond spins control the electron spin dynamics in CdSe quantum dots with 1-octanethiol. Inhomogeneous dephasing limits the spin coherence time in larger transverse magnetic fields for both hole acceptor cases, but with distinct different -factor inhomogeneity. These findings manifest that surface conditions play an important role in the spin dynamics and that thereby the surface and its surroundings can be exploited to control the spin in colloidal nanostructures.
通过时间分辨椭圆偏振光谱研究了含空穴受体的CdSe量子点中的电子自旋动力学。两种类型的空穴受体，即Li[EtBH]和1-辛烷硫醇，导致明显不同的电子自旋动力学。差异包括电子因子、自旋退相/弛豫时间和机制。在含有Li[EtBH]的CdSe量子点中，电子自旋退相和弛豫在零磁场和弱磁场中由电子-核超精细相互作用主导。相比之下，超精细相互作用、电子载流子寿命以及电子与空穴或表面悬挂键自旋之间的交换相互作用控制着含有1-辛烷硫醇的CdSe量子点中的电子自旋动力学。对于两种空穴受体情况，非均匀退相在较大横向磁场中限制了自旋相干时间，但具有明显不同的因子不均匀性。这些发现表明表面条件在自旋动力学中起着重要作用，因此可以利用表面及其周围环境来控制胶体纳米结构中的自旋。
