Dzhagan V M, Valakh M Ya, Raevska O E, Stroyuk O L, Kuchmiy S Ya, Zahn D R T
Institute of Semiconductors Physics, National Academy of Science of Ukraine, 03028 Kyiv, Ukraine.
Nanotechnology. 2009 Sep 9;20(36):365704. doi: 10.1088/0957-4484/20/36/365704. Epub 2009 Aug 18.
The effect of shells of various thicknesses on the vibrational resonant Raman spectra of CdSe/ZnS core-shell nanoparticles is studied. The dependence of the core-shell structure on the method of shell deposition is derived from a comparison of the vibrational and photoluminescence spectra of nanoparticles. Along with the appearance of peaks attributed to the shell, the phonon spectrum of the core undergoes significant changes upon shell growth. The change of the CdSe LO peak lineshape in core-shell nanoparticles is discussed with respect to possible changes in the spectrum of both optical and acoustical phonons upon shell formation. Based on the observed decrease of the CdSe 2LO/LO peak intensity ratio, a weakening of exciton coupling to the CdSe LO phonon upon ZnS shell deposition is supposed. The change in the carrier localization volumes upon shell formation is discussed as a possible reason for the reduced coupling.
研究了不同厚度的壳对CdSe/ZnS核壳纳米颗粒振动共振拉曼光谱的影响。通过比较纳米颗粒的振动光谱和光致发光光谱，得出核壳结构对壳层沉积方法的依赖性。随着归属于壳层的峰的出现，在壳层生长时，核的声子谱会发生显著变化。针对壳层形成时光学声子和声学声子谱可能发生的变化，讨论了核壳纳米颗粒中CdSe LO峰线形的变化。基于观察到的CdSe 2LO/LO峰强度比的降低，推测在ZnS壳层沉积时激子与CdSe LO声子的耦合减弱。讨论了壳层形成时载流子局域体积的变化，作为耦合降低的可能原因。
