中文摘要：

利用交叉偏振三阶非线性瞬态光栅技术，研究了室温下CdTe胶体量子点激子自旋弛豫动力学的尺寸效应.在抽运-探测光子能量与CdTe量子点的最低激子吸收（1Se-1Sh）跃迁相共振时，量子点激子自旋弛豫显示了时间常数为0.1-0.5 ps的单指数衰减行为. CdTe量子点激子自旋的快速弛豫源于亮暗激子精细结构态跃迁，即J =±1←→-＋2跃迁.激子自旋弛豫主要由空穴的自旋翻转过程决定.研究结果表明： CdTe量子点激子自旋弛豫速率与量子点尺寸的4次方成反比.

英文摘要：

Size-dependent exciton spin relaxation dynamics in CdTe colloidal quantum dots is studied at room temperature with the cross-polarized heterodyne third-order nonlinear transient grating technique The CdTe exciton spin relaxation reveals a mono-exponential decay behavior with a time constant of 0.1-0.5 ps when the pump-probe photon energy is tuned to be in resonance with the lowest exciton absorption transition （1Se-1Sh）. The exciton spin relaxation in quantum dot is mainly governed by the hole spin flip process and ascribed to the transitions between bright-dark exciton fine structure states, i.e. J =±1←→-＋2. This finding suggests that the exciton spin relaxation rate in CdTe quantum dot is inversely proportional to the fourth power of quantum dot size.