172 resultados para EU2
Resumo:
Eu2+-doped high silica glass (HSG) is fabricated by sintering porous glass which is impregnated with europium ions. Eu2+-doped HSG is revealed to yield intense blue emission excited by ultraviolet (UV) light and near-infrared femtosecond laser. The emission profile obtained by UV excitation can be well traced by near-infrared femtosecond laser. The upconversion emission excited by 800 nm femtosecond laser is considered to be related to a two-photon absorption process from the relationship between the integrated intensity and the pump power. A tentative scheme of upconverted blue emission from Eu2+-doped HSG was also proposed. The HSG materials presented herein are expected to find applications in high density optical storage and three-dimensional color displays. (c) 2008 American Institute of Physics.
Resumo:
KMgF3F EuEu^3Eu^2100029KMgFX1h100hKMgF3Eu^2X360nmKMgF310^3Gy30dKMgF3Eu^2360nm
Resumo:
-Y2SiO5Eu^3Y2SiO5Y2SiO5260-270nm320nmFO^-YSOEu^3Y2SiO5FOEu^2300nm390nmEu^3Y2SiO5
Resumo:
The absorption spectra of the undoped Y2SiO5 and Eu3+-doped Y2SiO5 crystals grown by the Czochralski technique were compared before and after annealing and, similarly, the unannealed and annealed crystals after gamma-ray irradiation. The absorption bands of Eu2+ ions with peaks at 300 and 390 nm were observed in the as-grown Y2SiO5:Eu3+ crystal. These peaks were more intense in H-2-annealed and irradiated Y2SiO5:Eu3+ crystals. The additional absorption peaks at 260 and 320-330 nm which were attributed to F color centers and O- hole centers were observed in irradiated undoped Y2SiO5 and Y2SiO5:Eu3+ crystals, respectively. (c) 2005 Elsevier B.V. All rights reserved.
Resumo:
Quasi-aligned Eu2+-doped wurtzite ZnS nanowires on Au-coated Si wafers have been successfully synthesized by a vapor deposition method under a weakly reducing atmosphere. Compared with the undoped counterpart, incorporation of the dopant gives a modulated composition and crystal structure, which leads to a preferred growth of the nanowires along the [0110] direction and a high density of defects in the nanowire hosts. The ion doping causes intense fluorescence and persistent phosphorescence in ZnS nanowires. The dopant Eu2+ ions form an isoelectronic acceptor level and yield a high density of bound excitions, which contribute to the appearance of the radiative recombination emission of the bound excitons and resonant Raman scattering at higher pumping intensity. Co-dopant Cl- ions can serve not only as donors, producing a donor-acceptor pair transition with the Eu2+ acceptor level, but can also form trap levels together with other defects, capture the photoionization electrons of Eu2+, and yield long-lasting (about 4 min), green phosphorescence. With decreasing synthesis time, the existence of more surface states in the nanowires forms a higher density of trap centers and changes the crystal-field strength around Eu2+. As a result, not only have an enhanced Eu2+ -4f(6)5d(1)-4f(7) intra-ion transition and a prolonged afterglow time been more effectively observed (by decreasing the nanowires' diameters), but also the Eu2+ related emissions are shifted to shorter wavelengths.
Resumo:
The pressure dependence of the photoluminescence from ZnS : Mn2+, ZnS : Cu2+, and ZnS : Eu2+ nanoparticles were investigated under hydrostatic pressure up to 6 GPa at room temperature. Both the orange emission from the T-4(1) - (6)A(1) transition of Mn2+ ions and the blue emission from the DA pair transition in the ZnS host were observed in the Mn-doped samples. The measured pressure coefficients are -34.3(8) meV/GPa for the Mn-related emission and -3(3) meV/GPa for the DA band, respectively. The emission corresponding to the 4f(6)5d(1) - 4f(7) transition of Eu2+ ions and the emission related to the transition from the conduction band of ZnS to the t(2) level of Cu2+ ions were observed in the Eu- and Cu-doped samples, respectively. The pressure coefficient of the Eu-related emission was found to be 24.1(5) meV/GPa, while that of the Cu-related emission is 63.2(9) meV/GPa. The size dependence of the pressure coefficients for the Mn-related emission was also investigated. The Mn emission shifts to lower energies with increasing pressure and the shift rate (the absolute value of the pressure coefficient) is larger in the ZnS : Mn2+ nanoparticles than in bulk. Moreover, the absolute pressure coefficient increases with the decrease of the particle size. The pressure coefficients calculated based on the crystal field theory are in agreement with the experimental results. (C) 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Resumo:
LEDLEDLEDLEDLEDLEDYAG:CeUVLEDLED LED 1. LEDEu2+HTP-Ca3SiO4Cl2:Eu2+LEDHTP-Ca3SiO4Cl2 2. Eu2+LEDLTP-Ca3SiO4Cl2:Eu2+LED 3. LEDEu2+Li2CaSiO4:Eu2+LED 4. CaMoO4:Eu3+CaMoO4:Eu3+3LED
Resumo:
Eu2+Ce3+Eu2+Eu2+Eu2+Ce3+4f~(n+1) 4f ~n5d~1Eu2+Ce3+StokesStokesBa2MgB2O6, BaBe2B2O6 1 Ba2LiB5OjoSrB4O7Stokes shift vs FcSrA12B207BaLiBO3CaSiO3 1SrSiO3 , BaSiO3Sr2LiSiO4F, BasS1O4BrBaSSiO4ClStokes
Resumo:
srB4O7BO4MBPO5MCaSrBaPO404BaSO4SO4Eu3+Eu2+ Sr4Al14O25AIO4BaMgsiO4SiO4Eu3+Eu2+Eu3+Eu2+BaMgSiO4Eu2+Eu2+Ba3Eu2+398nmBa1Ba2Eu2+500nmBaMgSiO4Eu2+Eu2+500nmBlasseSAll4025SrAl2O4Sr3A12O6Sr4Al4O25SrAl2O4Eu3+Eu2+Sr3A12O6Eu3Eu2Sr4Al14O25BaMgSiO4Sr3Al2O6SAll 4025BaMgsi04Sr3Al2O6Ce4Ce3+Sr4Al14O25Ce3Tb3+Eu2+Ce3Tb3+Eu2Sr4Al14O25BaMgSiO4Sr3Al2O6CaYBO4Tb35D35D4254nmCaYBO4Eu3+609nmBaMgsio4Ce3371nm
Resumo:
MAIF5MCaSrBaLIMAIFaMCaSrCaAIFSrAIFBaAICaAIF6LrAISrAlF5LiSrAlF6llCoAIF6BaAlF5LiCaAlF6KMgF3:EuKMgFa:EU6P7/28S7/2420nml6P7/2-8S7/2Eu3+GdEuKMgFaBaLiF3BaY2F8Gd2+Eu2+Gd3+Eu2+Gd3+Eu2+Pr+ KMgF2LiYF4BaY2F8KMgFa:Pr3+352nmPr3+KMg1-xCaxF3Pr3+Ca2MgSi2O2EuEu3+Eu2+Ca2Eu8Si6O26X-ray
Resumo:
4fN-1n'l'4fN-1n'l'6604fN-1n'l'n'l'=5d6s6p4fN-1n'l'fN-15d4fN-15dfdhe[fciaiQi2]1/2Dy3+Tb3+fCe3+Eu2+4fN-15dheheCe3+Ey2+4fN-15dCe3+Eu2+4fN-15dFcEhQfi/NFc10Dq4fN-15dCe3+Eu2+heFc4fN-1n'l
Resumo:
Eu2+ab-Zn3(PO4)2:Mn2+-Zn3PO42:Mn2+Zn3B2O6:Mn2+Y2O3Eu3+Ca8MgSiO44Cl2:Eu2+Zn4B6O13:Mn2+-Zn3(PO4)2Mn2+Zn2SiO4:Mn2+Y2O2S:Eu3+caOEu3-Zn3(PO4)2:Mn2+Ga3+Zn2SiO4:Mn2+Al3+
Resumo:
The photoluminescence (PL) and photostimulated luminescence (PSL) of BaFBr: Eu phosphors are reported. In the photoluminescence of BaFBr:Eu, the emission of Eu2+, e-h recombination and Eu3+ have been observed, while in the photostimulated luminescence only the emission of Eu2+ was observed. This phenomenon may be explained well by the suggestion of a two-hand model for the host emission in which the host emission energy may transfer to Eu2+ difference of excitation in those two processes results in different transfer rates which makes the PL and PSL emission different.
Resumo:
Long lasting phosphorescence (LLP) was observed in Eu2+, Ce3+ co-doped strontium borate glasses prepared under the reducing atmosphere due to the emission of both Eu2+ and Ce3+. The methods of photoluminescence, thermoluminescence and phosphorescence were used to study the samples, and possible mechanism was suggested. The co-doping of Ce3+ ions poisoned the phosphorescence emission of Eu2+ because of the competition to obtain the trapped electron. The phosphorescence of Ce3+ in the sample decays more quickly than that of Eu2+, which is suggested for the reason that the emission energy of Ce3+ is higher or the distance between Ce3+ and electron traps of the glasses is longer.
Resumo:
In this study, KMgF3:Eu2+ luminescent nanocrystals (NCs) were prepared in water/cetyltrimethylammonium bromide (CTAB)/2-octanol microemulsions. The KMgF3:Eu2+ NCs were characterized by transmission electron microscopy (TEM), X-ray diffractometer (XRD), fluorescence spectrum, infrared spectroscopy (IR) and elementary analysis. The results showed that the size of the KMgF3:Eu2+ NCs was hardly affected by water content and surfactant (CTAB) concentration. The emission spectrum showed that the position of the 362 nm peak is due to the K+ sites substituted Eu2+. Two emission peaks located at 589 and 612 nm can be attributed to Eu3+, which exist at two different types of Eu3+ centers: one is Eu3+ at a K+ site, the other is clustering of Eu3+ ions in the interstices of KMgF3 host lattice.
