Spectral control of plasmonic emission enhancement from quantum dots near single silver nanoprisms

The near-field effects of plasmonic optical antennas are being explored in applications ranging from biosensors to solar cells. We demonstrate that photoluminescence emission enhancement from CdSe quantum dots (QDs) can be obtained in the absence of any excitation enhancement near single silver nanoprisms. The spectral dependence of the radiative and nonradiative decay rate of the QDs closely follows the silver nanoparticle plasmon scattering spectrum. Using both experiment and theory we show that, in the absence of excitation enhancement, the ratio of radiative to nonradiative decay rate enhancement is proportional to the silver nanoparticle scattering efficiency. These results provide guidelines both for separating excitation and emission enhancement effects in sensing and device applications and for tailoring emission enhancement effects using plasmonic nanostructures.