IBM Research -Zurich, Säumerstrasse 4, 8803 Rüschlikon, Switzerland.
Nano Lett. 2012 Oct 10;12(10):5224-9. doi: 10.1021/nl302390b. Epub 2012 Oct 1.
Exciton dynamics within the band-edge state manifold of CdSe/ZnS and CdSe/CdS quantum dots (QDs) have been investigated. Low-temperature time-resolved photoluminescence (PL) experiments demonstrate that exciton relaxation is mediated by LO phonons, whereas an acoustic phonon bottleneck is observed for splitting energies lower than the optical phonon energy. This has important implications since the main source affecting exciton dephasing is considered to be a spin-flip process. Our results concur with recent observations of long exciton dephasing times in CdSe/CdS QDs and show a way to engineer nanoparticles with enhanced coherence time, a prerequisite for their use in quantum optical applications.
我们研究了 CdSe/ZnS 和 CdSe/CdS 量子点（QDs）中带边态中的激子动力学。低温时间分辨光致发光（PL）实验表明，激子弛豫是通过 LO 声子介导的，而对于分裂能低于光学声子能量的情况，则观察到了声子瓶颈。这具有重要意义，因为影响激子退相的主要来源被认为是自旋翻转过程。我们的结果与最近在 CdSe/CdS QDs 中观察到的长激子退相时间一致，并展示了一种工程化具有增强相干时间的纳米粒子的方法，这是它们在量子光学应用中使用的前提条件。
