title: Metal-enhanced upconversion luminescence tunable through metal nanoparticle-nanophosphor separation.
abstract: We have demonstrated amplification of luminescence in upconversion nanophosphors (UCNPs) of hexagonal phase NaYF(4) (β-NaYF(4)) doped with the lanthanide dopants Yb(3+), Er(3+) or Yb(3+), Tm(3+) by close proximity to metal nanoparticles (NPs). We present a configuration in which close-packed monolayers of UCNPs are separated from a dense multilayer of metal NPs (Au or Ag) by a nanometer-scale oxide grown by atomic layer deposition. Luminescence enhancements were found to be dependent on the thickness of the oxide spacer layer and the type of metal NP with enhancements of up to 5.2-fold proximal to Au NPs and of up to 45-fold proximal to Ag NPs. Concomitant shortening of the UCNP luminescence decay time and rise time is indicative of the enhancement of the UCNP luminescence induced by resonant plasmonic coupling and nonresonant near-field enhancement from the metal NP layer, respectively.
authors.affiliation: Department of Electrical and Systems Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
authors.forename: Marjan
authors.initials: M
authors.lastname: Saboktakin
authors.forename: Xingchen
authors.initials: X
authors.lastname: Ye
authors.forename: Soong Ju
authors.initials: SJ
authors.lastname: Oh
authors.forename: Sung-Hoon
authors.initials: SH
authors.lastname: Hong
authors.forename: Aaron T
authors.initials: AT
authors.lastname: Fafarman
authors.forename: Uday K
authors.initials: UK
authors.lastname: Chettiar
authors.forename: Nader
authors.initials: N
authors.lastname: Engheta
authors.forename: Christopher B
authors.initials: CB
authors.lastname: Murray
authors.forename: Cherie R
authors.initials: CR
authors.lastname: Kagan
mesh_terms: D003460:Crystallization / Q000379:methods*; D008163:Luminescent Measurements / Q000379:methods*; D046911:Macromolecular Substances / Q000737:chemistry; D008422:Materials Testing; D053768:Metal Nanoparticles / Q000737:chemistry*; D008968:Molecular Conformation; D010316:Particle Size; D013499:Surface Properties
chemical_list: D046911:Macromolecular Substances