title: Surface-plasmon-coupled emission of quantum dots.
abstract: We studied surface plasmon-coupled emission (SPCE) of semiconductor quantum dots (QDs). These QDs are water-soluble ZnS-capped CdSe nanoparticles stabilized using lysine cross-linked mercaptoundecanoic acid. The QDs were spin-coated from 0.75% PVA solution on a glass slide covered with 50 nm of silver and a 5-nm protective SiO(2) layer. Excited QDs induced surface plasmons in a thin silver layer. Surface plasmons emitted a hollow cone of radiation into an attached hemispherical glass prism at a narrow angle of 48.5 degrees. This directional radiation (SPCE) preserves the spectral properties of QD emission and is highly p-polarized irrespective of the excitation polarization. The SPCE spectrum depends on the observation angle because of the intrinsic dispersive properties of SPCE phenomenon. The remarkable photostability can make QDs superior to organic fluorophores when long exposure to the intense excitation is needed. The nanosize QDs also introduce a roughness near the metal layer, which results in a many-fold increase of the coupling of the incident light to the surface plasmons. This scattered incident illumination transformed into directional, polarized radiation can be used simultaneously with SPCE to develop devices based on both quantum dot emission and light scattered from surface plasmons on a rough surface.
authors.affiliation: Center for Fluorescence Spectroscopy, Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA.
authors.forename: Ignacy
authors.initials: I
authors.lastname: Gryczynski
authors.forename: Joanna
authors.initials: J
authors.lastname: Malicka
authors.forename: Wen
authors.initials: W
authors.lastname: Jiang
authors.forename: Hans
authors.initials: H
authors.lastname: Fischer
authors.forename: Warren C W
authors.initials: WC
authors.lastname: Chan
authors.forename: Zygmunt
authors.initials: Z
authors.lastname: Gryczynski
authors.forename: Wojciech
authors.initials: W
authors.lastname: Grudzinski
authors.forename: Joseph R
authors.initials: JR
authors.lastname: Lakowicz
mesh_terms: D019187:Cadmium Compounds / Q000737:chemistry; D053758:Nanoparticles / Q000737:chemistry; D045663:Quantum Dots; D018036:Selenium Compounds / Q000737:chemistry; D012666:Semiconductors; D012680:Sensitivity and Specificity; D012822:Silicon Dioxide / Q000737:chemistry; D012834:Silver / Q000737:chemistry; D012995:Solubility; D013440:Sulfides / Q000737:chemistry; D020349:Surface Plasmon Resonance / Q000379:methods*; D013499:Surface Properties; D014867:Water / Q000737:chemistry; D017967:Zinc Compounds / Q000737:chemistry
chemical_list: D019187:Cadmium Compounds; D018036:Selenium Compounds; D013440:Sulfides; D017967:Zinc Compounds; D014867:Water; D012834:Silver; D012822:Silicon Dioxide; C058667:cadmium selenide; C031238:zinc sulfide