Optical Properties of Surface Passivated CdS Nanocrystals Bifunctionally Anchored to Ag Nanoparticles

摘要

In this paper, optical properties of bifuctionally capped CdS nanocrystals and after addition of Ag nanoparticles (NPs) was studied. Capping agents used in this study were mercaptoundecanoic acid (MUA), Cysteine (Cys) and mercaptoethanol (ME). The bifunctional capping agents were chosen so that one end (thiol functionality) can bind to CdS nanocrystal and other end to Ag NPs. It was observed from photoluminescence studies that capping with bifunctional molecules as well as subsequent addition of Ag NPs results in increased fluorescence intensity. The successful bifunctional capping with other capping agents MUA and Cys as well as formation of Ag-CdS hybrid system were demonstrated by Fourier Transform Infrared spectrophotometer (FTIR). The enhanced photoluminescence intensity shown by Ag-CdS hybrid system is as a result of metal enhanced fluorescence. It was also demonstrated that CdS-Cys-Ag nanocrystal can detect hemin with change in optical properties and the minimum detectable change occurs at 382 nM.