CdSe/CdS核壳量子点拉曼光谱的表面模分析

Surface optical phonon mode study of CdSe/CdS core shell quantum dots

研究了不同壳层厚度（0～5．5ML）的CdSe／CdS核壳量子点的一次和高次拉曼散射，具体分析了CdSe和CdS的表面模随着壳层厚度的变化情况。结果表明，随着壳层厚度的增加，CdSe表面模（S01）从198cm^-1频移到185cm^-1，CdS的表面模（SO2）从275cm^-1频移到267cm^-1，并且SO1和SO2试验结果与由介电连续模型得到的理论值很接近。此外，根据CdSe表面模的频移，对随着CdS壳层厚度的增加而引起的核层（CdSe）的介电常数随环境的变化做出了修正。

The evolution of the surface optical phonon mode of CdSe/CdS core shell quantum dots with an increase of the shell thickness from 0 to 5.5 monolayers has been studied by Raman spectroscopy. The shift of the surface optical mode of CdSe （SO1） from 198-185cm^-1 and that of CdS （SO2） from 275-267cm^-1 were observed and agreed well with the theoretical values deduced by the dielectric continuum model. Besides, the variation of dielectric environment of CdSe core layer with the increasing CdS shell thickness is modified according to the shift of SO1.