title: Visible upconversion emission of Pr3+ doped gadolinium gallium garnet nanocrystals.
abstract: The luminescence properties of a Pr3+-doped gadolinium gallium garnet (GGG, Gd3Ga5O12) nanocrystalline host were investigated. Dominant blue/green emission was observed emanating from the 3P0 --> 3H4 transition after excitation using a wavelength of 457.9 nm. Continuous wave excitation into the 1D2 level of the Pr3+ ion at 606.9 nm transition produced blue upconversion luminescence spectra, ascribed to emission from the 3P1 --> 3H4 and 3P0 --> 3H4 transitions. The increase in the decay times of the observed transitions following excitation with 606.9 nm is indicative of the dominance of an energy transfer upconversion (ETU) mechanism relative to excited state absorption (ESA). Furthermore, blue, green and red upconversion emission was observed from the 3P0, 3P1 and 1D2 states following excitation into the 1G4 energy level with 980 nm. No change in the decay times of the emitting states was observed following excitation with a wavelength of 980 or 457.9 nm; hence, upconversion was determined to primarily occur through ESA. The luminescence properties of the nanocrystals are compared to a single crystal of GGG:Pr3+ (bulk) with an identical Pr3+ concentration (1%).
authors.affiliation: Department of Chemistry and Biochemistry, Concordia University, Montreal, Quebec, H4B 1R6, Canada.
authors.forename: R
authors.initials: R
authors.lastname: Naccache
authors.forename: F
authors.initials: F
authors.lastname: Vetrone
authors.forename: J C
authors.initials: JC
authors.lastname: Boyer
authors.forename: J A
authors.initials: JA
authors.lastname: Capobianco
authors.forename: A
authors.initials: A
authors.lastname: Speghini
authors.forename: M
authors.initials: M
authors.lastname: Bettinelli
mesh_terms: D003460:Crystallization / Q000379:methods*; D004735:Energy Transfer; D005682:Gadolinium / Q000737:chemistry* / Q000528:radiation effects; D005708:Gallium / Q000737:chemistry* / Q000528:radiation effects; D008027:Light; D008163:Luminescent Measurements / Q000379:methods*; D008422:Materials Testing; D049329:Nanostructures / Q000737:chemistry* / Q000528:radiation effects*; D036103:Nanotechnology / Q000379:methods; D010777:Photochemistry / Q000379:methods; D011221:Praseodymium / Q000737:chemistry* / Q000528:radiation effects
chemical_list: D005682:Gadolinium; D005708:Gallium; D011221:Praseodymium