CdS/聚电解质核-壳式复合微球的光谱特性研究

Study on Spectral Characteristics of CdS/Polyelectrolyte Core-Shell Composite Microspheres

合成了CdS/聚电解质核-壳式复合微球并研究了其红外光谱、拉曼光谱和真空紫外光谱。在复合微球的红外光谱中出现的619.1 cm-1Cd—S伸缩振动峰,与固态CdS相比出现了明显的蓝移现象。拉曼光谱中,与CdS特征纵光学声子模(1LO)相对应的299.4 cm-1也发生了蓝移现象。常温(290 K)和低温(20 K)下的真空紫外光谱存在差异。对于激发光谱,常温下主峰在269 nm,并有一些副峰,而低温下仅在253 nm处有1个明显的激发峰;常温下的发光峰在382 nm,并且有322、542和585 nm的副峰,而低温下则在394 nm处有明显的发光峰。这些结果说明CdS和聚电解质之间形成了包裹关系,并且具有很好的光学性能,可以作为荧光量子点标记材料。

CdS/polyelectrolyte core - shell composite microspheres （CdS/PCCM） were prepared by layer-by-layer self-assembly technique, and their spectral characteristics were studied by infrared （IR）, Raman and vacuum ultraviolet （VUV） spectroscopic techniques. From the IR spectrum of CdS/PCCM, a Cd--S stretching vibration peak was observed at 619. 1 cm^-1 which was evidently blue-shifted comparing with that of solid state CdS. The Raman spectrum of CdS/PCCM indicated that the characteristic longitudinal optical phonon mode （1LO） of CdS corresponding to 299.4 cm^-1 was also blue-shifted comparing with that of solid-state CdS. A big difference between the vacuum vio- let spectra of CdS/PCCM obtained under normal（290 K） and low（20 K） temperatures was observed. The excitation spectrum exhibited a maximum excitation peak at 269 nm with three side peaks at 322, 542 and 585 nm, respectively in normal temperature, but exhibited only one excitation peak at 253 nm in low temperature. The emission spectra of CdS/PCCM also exhibited a maximum emission peak at 382 nm with three small peaks at 322, 542 and 585 nm, respectively in normal temperature, but only one emission peak appeared at 394 nm in tow temperature. These results indicated that CdS/PC- CM had very good optical capability and could be used as labeling material of fluorescence quantum dots.