title: Hard proof of the NaYF(4)/NaGdF(4) nanocrystal core/shell structure.
abstract: Hexagonal-phase NaYF(4)/NaGdF(4) core/shell nanocrystals were synthesized and investigated by X-ray photoelectron spectroscopy (XPS) using tunable synchrotron radiation. Based on the ratio of the Y(3+) 3d to Gd(3+) 4d core level intensities at varying photoelectron kinetic energies, we conclude that Gd(3+) resides predominantly at the surface of the nanocrystals, proving a core/shell structure. These nanocrystals show potential for use as contrast agents in magnetic resonance imaging (MRI) applications and optical imaging.
authors.affiliation: Department of Chemistry, University of Victoria, P.O. Box 3065, Victoria, British Columbia, Canada, V8W 3V6.
authors.forename: Keith A
authors.initials: KA
authors.lastname: Abel
authors.forename: John-Christopher
authors.initials: JC
authors.lastname: Boyer
authors.forename: Frank C J M
authors.initials: FC
authors.lastname: van Veggel