Photoluminescence enhancement and quenching of single CdSe∕ZnS nanocrystals on metal surfaces dominated by plasmon resonant energy transfer

We studied the mechanism of the photoluminescence (PL) enhancement and quenching of single CdSe∕ZnS nanocrystals on rough Au surfaces. Single nanocrystal spectroscopy revealed that the PL enhancement depends strongly on the excitation wavelength and liner-polarization angle due to the localized plasmon excitation and is also sensitive to the nanocrystal size. The polarization- and size-dependent PL enhancement and quenching are determined by the balance between the resonant energy transfer from the nanocrystal to the Au surface and the electric field enhancement.