Charge-Sensitive Surface Optical Phonon in CdS Quantum Dots Studied by Resonant Raman Spectroscopy

Abstract

The probe of surface properties of quantum dots (QDs) is of great importance as the surface properties of QDs greatly influence their performance in photoelectronic devices and photocatalysis. In this work, resonant Raman spectroscopy was used to study the surface optical (SO) phonon of CdS QDs. It was found that the intensity of SO phonon peak of CdS QDs increased as the size of the QDs decreased, but the dielectric constant of the surrounding media, which showed striking impacts on SO phonon peak in previous publications, has no visible influence in our experiments. Meanwhile, the intensity of SO phonon peak changes obviously when the surface ligands of CdS QDs or the excitation power/wavelength is changed. Besides, the loading of platinum catalyst seriously weakens the intensity of SO phonon peak. These experimental results can be interpreted with a charge-sensitive surface optical phonon model.