Surface-enhanced Raman spectroscopy of CdSe quantum dots on nanostructured plasmonic surfaces

Abstract

Although quantum dots (QDs) are widely used as fluorophores they have not so far been used as Raman labels. Here we demonstrate (resonant) surface-enhanced Raman scattering (SERS) of CdSe QDs attached to nanostructured plasmonic surfaces. The 208 cm−1 CdSe longitudinal optical phonon mode is observed for laser excitation at 514, 633, and 785 nm. Tuning the SERS signal into resonance with the localized surface plasmon reveals the effects of optical absorption and emission on QD SERS. Equivalent tuning of the localized plasmons on graded nanovoid samples shows strong resonant SERS enhancements. These results pave the way for exploiting QDs as SERS markers.