title: Upconversion emission tuning from green to red in Yb3+/Ho3+-codoped NaYF4 nanocrystals by tridoping with Ce3+ ions.
abstract: Upconversion (UC) emission tuning from green to red in monodisperse NaYF(4):Yb(3+)/Ho(3+) nanocrystals was successfully achieved by tridoping with Ce(3+) ions under diode laser excitation of 970 nm. It is proposed that two efficient cross-relaxation processes, 5S2/5F4(Ho) + 2F(5/2)(Ce) --> 5F5(Ho) + 2F(7/2)(Ce) and 5I6(Ho) + 2F(5/2)(Ce) --> 5I7(Ho) + 2F(7/2)(Ce)between Ho(3+) and Ce(3+) ions, have been employed to select UC pathways to tune the UC radiation. Theoretical investigations based on steady-state equations demonstrate the proposed UC mechanisms and explain well the observed linear increase of the UC red-to-green intensity ratio with the increment of Ce(3+) ion concentrations.
authors.affiliation: Department of Physics, Harbin Institute of Technology, 150001 Harbin, People's Republic of China.
authors.forename: Guanying
authors.initials: G
authors.lastname: Chen
authors.forename: Haichun
authors.initials: H
authors.lastname: Liu
authors.forename: Gabriel
authors.initials: G
authors.lastname: Somesfalean
authors.forename: Huijuan
authors.initials: H
authors.lastname: Liang
authors.forename: Zhiguo
authors.initials: Z
authors.lastname: Zhang
mesh_terms: D000465:Algorithms; D002586:Cesium / Q000737:chemistry*; D005459:Fluorides / Q000737:chemistry*; D005461:Fluorine / Q000737:chemistry; D006695:Holmium / Q000737:chemistry*; D007455:Iodine / Q000737:chemistry; D007834:Lasers; D008163:Luminescent Measurements; D053768:Metal Nanoparticles / Q000737:chemistry*; D046529:Microscopy, Electron, Transmission; D008956:Models, Chemical; D019265:Spectroscopy, Near-Infrared; D013455:Sulfur / Q000737:chemistry; D014961:X-Ray Diffraction; D015018:Ytterbium / Q000737:chemistry*; D015019:Yttrium / Q000737:chemistry*
chemical_list: C525362:sodium yttriumtetrafluoride; D002586:Cesium; D005461:Fluorine; D015019:Yttrium; D013455:Sulfur; D007455:Iodine; D015018:Ytterbium; D005459:Fluorides; D006695:Holmium