Browsing by Subject "Luminescence emission"
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Item Luminescence behavior and Raman characterization of jade from Turkey(2011) Tuncer Arslanlar Y.; Garcia-Guinea J.; Kibar R.; Çetin A.; Ayvacikli M.; Can N.Results are presented for the cathodoluminescence (CL), radioluminescence (RL) and thermoluminescence (TL) of jade from Turkey. Jade samples show broad band luminescence from green to red, which, using lifetime-resolved CL, reveals seven overlapping emissions, of which two are dominant. Green emission obtained using spatially resolved CL was associated with Mn2+ and emission bands centered near at 480 and 530nm were attributed to 3P0-3H4 and 1D2-3H4 transitions of Pr3+, respectively. Different shifts of the peak-wavelengths for 326 and 565nm were observed with varying jade compositions. The incorporation of the larger K ion causes non-linear variations of the cell dimensions and therefore changes in the Fe-O band distance. We suggest that stress of the jade structure can be linked to the luminescence emission at 326nm. Raman spectra have also been recorded in order to provide an unequivocal identification of the type of jade. The mechanism for the luminescence of the jade is considered. © 2011 Elsevier Ltd.Item Radioluminescence study of rare earth doped some yttrium based phosphors(Elsevier B.V., 2012) Ayvacikli M.; Ege A.; Ekdal E.; Popovici E.-J.; Can N.This paper reports the luminescence emission spectra of Y(Ta,Nb)O 4 activated by rare earth ions such as Eu3+ and Tb 3+. The influence of these rare earth ions on the radioluminescence (RL) of yttrium niobate and tantalate phosphors was investigated. The luminescent properties were studied under X-ray and preliminary RL measurements to further evaluate prepared materials. The emission centers of the rare earth activators (Eu3+, Tb3+) were found to contribute efficiently to the total luminescence. With their various luminescence chromaticities, these rare earth activated phosphors are promising materials for solid-state lighting applications as well as for X-ray intensifying screens in medical diagnosis, providing the broad band variation of visible RL from blue to red. © 2012 Elsevier B.V. All rights reserved.Item Spectral emission of rare earth (Tb, Eu, Dy) doped Y2Sn 2O7 phosphors(2013) Ege A.; Ayvacikli M.; Dinçer O.; Satilmiş S.U.Radioluminescence (RL) characterization of the yttrium stannate (Y 2Sn2O7) phosphors doped with 1 mol% Tb, Eu and Dy was carried out and significant electronic transitions corresponding to doped rare earth ions were observed. It was seen that all parts of these rare earth ions are included in the phosphor material in their trivalent state. The RL measurement indicates that the series of the emission-state 5D 4→7F6, 5D4→ 7F4, 5D4→7F 3, corresponding to the characteristic 4f→4f intra-configuration forbidden transitions of Tb3+are appeared and that main emission peak occurs at about 542 nm. There are in fact multiple emission lines at each of these due to the crystal field splitting of the ground state of the emitting ions. Eu-doped Y2Sn2O7 sample displayed intense and predominant emission peaks located at 580-650 nm corresponding to the 5D0→7Fj (j=l, 2, 3 and 4) transitions. Red emission coming from the hypersensitive Dy doped phosphor presented luminescence emissions with dominating transitions at 4F9/2→6Hj (j=9/2, 11/2, 13/2 and 15/2). The sharp emission properties show that the Y2Sn 2O7 is a suitable host for rare-earth ion doped phosphor material. © 2013 Elsevier B.V.Item Optical spectroscopy of the Ce-doped multicomponent garnets(Elsevier Ltd, 2016) Canimoglu A.; Karabulut Y.; Ayvacikli M.; Muresan L.E.; Perhaita I.; Barbu-Tudoran L.; Garcia Guinea J.; Karali T.; Can N.Here, we report our results referring to the preparation of Ce doped Y2.22MgGa2Al2SiO12, Y1.93MgAl4SiO12 and Y2.22Gd0.75Ga2Al3O12 using solid state reaction at high temperature. Several complementary methods (i.e. powder x-ray diffraction (XRPD), energy dispersive analysis of X-rays (EDX), scanning electron microscopy (SEM) and Fourier transforms infrared spectroscopy (FTIR)) were studied to examine the effects of the synthesis procedure on the morphology and structure. XRD analyses revealed that all compounds include yttrium aluminate phase with garnet structure. Cathodoluminescence (CL), radioluminescence (RL) and photoluminescence (PL) measurements were carried out for clarification of relationship between host lattice defects and the spectral luminescence emissions. Luminescence emission of phosphors is peaked at 530 nm assigned to 5d-4f transitions of the dopant Ce3+ ions with a broad emission band in 400-700 nm range. Under electron irradiation, the emission spectrum of Ce doped (YGd)3Ga2Al3O12 is well defined and has a characteristic fairly narrow and sharp emission band peaking at 312 nm and 624 nm corresponding to transition of 6P7/2 →8S7/2 and 6GJ→6PJ (Gd3+), respectively. We suggest some of phosphors might be excellent phototherapy phosphor materials under electron excitation. © 2016 Elsevier Ltd.Item Experimental and numerical optical characterization of plasmonic copper nanoparticles embedded in ZnO fabricated by ion implantation and annealing(Elsevier Ltd, 2016) Le K.Q.; Nguyen H.P.T.; Ngo Q.M.; Canimoglu A.; Can N.Here we describe the successfully fabrication of metal nanoparticle crystals by implanting copper (Cu) ions into single zinc oxide (ZnO) crystals with ion energy of 400 keV at ion doses of 1 × 1016 to 1 × 1017 ions/cm2. After implantation and post-annealing treatment, the Cu implanted ZnO produces a broad range of luminescence emissions, ranging from green to yellow. A green luminescence peak at 550 nm could be ascribed to the isolated Cu ions. The changes in luminescence emission bands between the initial implant and annealed suggest that the implants give rise to clustering Cu nanoparticles in the host matrix but that the annealing process dissociates these. Numerical modelling of the Cu nanoparticles was employed to simulate their optical properties including the extinction cross section, electron energy loss spectroscopy and cathodoluminescence. We demonstrate that the clustering of nanoparticles generates Fano resonances corresponding to the generation of multiple resonances, while the isolation of nanoparticles results in intensity amplification. © 2016 Elsevier B.V.Item Broadband luminescence of Cu nanoparticles fabricated in SiO2 by ion implantation(Elsevier Ltd, 2016) Nguyen T.K.; Le K.Q.; Canimoglu A.; Can N.In this study, we investigate optical properties of metal nanoparticle crystals fabricated by implanting copper (Cu) ions into single silica (SiO2) crystals with 400 keV at various ion doses. The Cu implanted SiO2 (SiO2:Cu) crystal produces a broadband luminescence emission, ranging from blue to yellow, and having a blue luminescence peak at 546 nm. Such anomalous luminescence emission bands suggest that the ion implantation may give rise to aggregation of Cu nanoparticles in the host matrix. The boundary element method-based modelling of a given Cu nanoparticle aggregation was employed to justify the broadband luminescence emission. Formation of Cu nanoparticles in SiO2 is predicted through their optical absorption data. The experimental results are compared with results of Mie calculations and we observe that the higher ion dose produces the larger particle size. © 2016 Elsevier Ltd