Resonant Raman effect enhanced by surface plasmon excitation of CdSe nanocrystals embedded in thin SiO2 films

Abstract

In this article, the Raman signal of CdSe nanocrystals well dispersed in a very thin SiO2 film (20 nm) has been investigated by surface plasmon excitation in a resonant Raman spectroscopy experiment. In order to perform the excitation, the thin SiO2 layer containing nanocrystals is deposited on a well-defined silver layer. The surface plasmon excitation increases the sensitivity of the Raman experiment, compared to the conventional setup, and allows the observation of a small number of nanocrystals (around 5000). The luminescence has also been measured and its dependence with the separation between the metal layer and CdSe nanocrystals is analyzed. In particular the quenching of the luminescence for thin film has been used to obtain only the Raman signal in resonant configuration.