Size analysis of CdSe/ZnS quantum dots in aqueous solution by using laser-induced breakdown detection

CdSe/ZnS quantum dots (QDs) coated with mercaptoacetic acid (MAA) in an anqueous solution are investigated by means of highly sensitive laser-induced breakdown detection (LIBD). In particular, a size distribution analysis of QDs dispersed in ultra pure water is performed as a function of time until a steady state is reached. Freshly prepared CdSe/ZnS-MAA QDs are found to initially exist as relatively large (25.0 × 1.2 nm) agglomerates that slowly disperse over days to small (6.5 × 0.2 nm), but stable, single particles. These results of increasing breakdown probability with increasing particle density amply demonstrate that LIBD can be a promising analytical technique for size analysis of nanoparticle formation and stability.