Investigation on preparation and fluorescence properties of oxy-fluoride glass co-doped with Er3+ and Yb3+

The glass sample based on the composition of 45PbF(2)-45GeO(2)-10WO(3) co-doped with Yb3+/Er3+ was prepared by the fusion method in two steps: melted at 950 degreesC for 20 similar to 25 min then annealed at 380 degreesC for 4 h. Through the V-prism it is found that the refractive index of host glass and the sample are 1.517 and 1.65 respectively. The transmittance was observed by using the ultraviolet-visible-infrared spectrometer in the wavelength range from 0.35 to 2.5mum. The transmittaitce of the host glass is beyond 73%. That of the sample is beyond 50% and there are characteristic absorption peaks of rare-earth ions. The emission spectrum was measured by using the Hitachi F-4500 fluorescent spectrometer pumped by 980 nm semiconductor laser. There are a strong emission peak at 530 nm and a weak peak at 650 nm.

Luminescent sol-gel thin films based on europium-substituted heteropolytungstates

Polyester thin films containing europium-substituted heteropolytungstate were obtained on quartz plate by the sol-gel method. The films exhibited the characteristic emission bands of the europium ion. The red to orange intensity ratio (R:O) of Eu3+ in the films increased as compared to the corresponding heteropolytungstate solids. The fluorescence lifetime of europium is shorter in the thin film than in the heteropolytungstate solid. The results indicated that the formation of europium-substituted heteropolytungstate/polyester thin film has great effect on the luminescence of europium- substituted heteropolytungstate.

Fabrication, characterization and conductivity of organic-inorganic hybrid Langmuir-Blodgett films based on polyquinoline and rare earth-substituted heteropolymolybdate

The organic/inorganic hybrid Langmuir-Blodgett (LB) films were obtained by the compact organization of poly(1,2-dihydro-2,2,4-trimethyl)quinoline (PQ), octadecylamine (ODA) and rare earth-substituted heteropolymolybdates. They were characterized by surface pressure-area (pi-A) isotherms, absorption spectra, fluorescence spectra, atomic force microscope (AFM) and scanning tunneling microscopy (STM). The atomic force microscope revealed a granular surface texture of nanosized rare earth-substituted heteropolymolybdate. The scanning tunneling microscopy indicated that the hybrid LB films containing rare earth-substituted heteropolymolybdates had the better electrical conductivity than LB film of PQ/ODA.

Luminescent Langmuir-Blodgett films based on Tiron-terbium

The luminescent ultrathin Langmuir-Blodgett (LB) films containing Tb-2(C6H3S2O8)(2) (Tiron-Tb) were successfully obtained. The modifications of compression isotherms of dimethyldioctadecylammonium bromide (DODA) have been observed when the Tiron-Tb complex was dissolved in the subphase. The effect of Tiron-Tb in the subphase on Langmuir films of DODA has been studied. Low-angle X-ray diffraction result indicates that the LB films have a good periodic layered structure. The UV and IR spectra results show the Tiron-Tb complex is incorporated into LB films layer-by-layer and the LB films are homogeneously deposited. The LB films containing Tiron-Tb can emit strong green luminescence, and the luminescence signal can be detected from a single layer. The luminescence properties of LB films have been discussed compared with those of the solutions.

Use of atomic force microscopy for imaging the initial stage of the nucleation of calcium phosphate in Langmuir-Blodgett films of stearic acid

The nucleation of calcium phosphate on the substrate of steatic acid Langmuir-blodgett film at the initial stage was investigated by atomic force microscopy. Nano-dots, nano-wires and nano-islands were observed in sequence for the first time, reflecting the nucleation of calcium phosphate and the molecular arrangement of carboxylic layer. The nucleation rates perpendicular and parallel to the carboxylic terminal group were estimated from the height and diameter of the calcium phosphate crystals, respectively. And this stage was distinct from the late explosive grown stage, in which the change of the morphology was not obvious. The approaches based on this discovery would lead to the development of new strategies in the controlled synthesis of inorganic nano-phases and the assembly of organized composite and ceramic materials.

Synthesis and characterization of new carbazole/fluorene-based derivatives for blue-light-emitting devices

2,7-Bis(9-ethylcarbazol-3-yl)-9,9-di(2-ethylhexyl)fluorene and a segmented copolymer composed of the same chromophores alternated with hexamethylene fragments were synthesized. The obtained materials possess good solubility in common organic solvents, high thermal stability with 1% weight loss temperature of 350-370 degrees C, and suitable glass transition temperatures. Both derivatives show blue fluorescence in dilute solutions as well as in solid state, demonstrating that excimers are not formed in the thin films. The fluorescence spectra of the materials do not show any peaks in the long-wavelength region even after annealing at 200 degrees C in air. An organic LED with the configuration of ITO/copolymer/Al generates blue electroluminescence with the maximum peak at 416 nm, rather low turn-on voltage (4.0 V), and brightness of about 400 cd/m(2). The heterostructure device based on model derivative emitted stable blue light with low operation voltage (100 cd/m(2) at similar to 11 V) and demonstrated luminescence efficiency of 0.8 cd/A.

Novel PPV-based light-emitting copolymers containing triazole moiety

Two new light-emitting PPV-based copolymers bearing electron-withdrawing triazole unit in the main chain have been synthesized by Wittig reaction between triazole diphosphonium salt and the corresponding dialdehyde monomers, respectively. Their optical and physical properties are characterized by UV-vis, photoluminescence (PL), TGA and DSC. The resulting copolymers are highly soluble in common organic solvents and have high Tg and Td values. They show blue-greenish fluorescence in solution (lambda(max) 502 and 508 nm) and green fluorescence in the solid state (lambda(max) 520 and 526 nm), respectively.

Zinc-based light-emitting materials containing oxadiazole moieties

Two oxadiazole-based zinc complexes containing naphthalene moiety with different coordination site are synthesized and characterized. Their thermal stability, photoluminescent and electroluminescent properties are investigated. The resulting complexes have good thermal stability and show bright blue fluorescence in the solid state. Their electroluminscent wavelengths are dependent on the coordination site of naphthalene moieties.

Luminescence properties of LB films based on heteropolytungstate of rare earth

In this work, the LB films based on heteropolytungstate of Dy and Sm have been prepared. The X-ray diffraction shows the LB films have a highly ordered lamella structure. The luminescence characteristics of the LB films were studied. The charge transfer bands of LB films are in higher energies than those of the corresponding solids. It is noticed that the yellow to blue intensity ratio (Y:B) of Dy3+ in the LB films is different from that of the solid. The differences in the spectra show that the Dy3+ site symmetry in LB film was changed due to the interaction between the surfactant and the polyanions. The differences could also be found in the luminescence spectra of the LB films of Sm complex.

Luminescent self-assembled thin films based on rare earth-heteropolytungstate

earth (Eu3+, Dy3+)-heteropolytungstate thin films were fabricated by self-assembly method successfully. The thin films give off strong fluorescence, which can be observed by eyes upon UV irradiation. The characteristic emission behaviors of the rare earth ions in self-assembled thin film were investigated compared with those of the corresponding solids. It is noticed that the intensity ratio between D-5(0) --> F-7(2) and D-5(0) --> F-7(1) of Eu3+ and the intensity ratio between F-4(9/2) --> H-6(13/2) and F-4(9/2) --> H-6(15/2) of Dy3+ in the self-assembled films are different from those of the corresponding solids. Furthermore, the self-assembled films present shorter fluorescence lifetimes than the corresponding solids. The reasons for these results have been discussed.

Langmuir-Blodgett films based on europium-substituted heteropolytungstate and their luminescence properties

Several new hybrid organic-inorganic Langmuir-Blodgett (LB) films containing europium-substituted hetero-polytungstate Eu (XW11O39)(2)''(-) (X=Ge, Si, B) were successfully obtained using LB technique. When the heteropolytungstate anions are dissolved in the subphase, dimethyldioctadecylammonium bromide compression isotherms have been modified, which shows that the polyanions interact with the monolayer. Y-type LB films were obtained from the systems. Low-angle X-ray has shown that these LB films have well-defined lamella. The LB films were characterized by luminescence spectra and the characteristic luminescence behavior for europium-substituted heteropolytungstate complexes and their LB films were discussed. The results of excitation spectra indicate that the energy could be effectively transferred from ligands to the Eu3+ ions in the LB films and the luminescence efficiency could be greatly increased. The results of luminescence spectra indicate that the formations of hybrid organic-inorganic LB films have a great effect on the luminescence of europium-substituted heteropolytungstate. The lifetime shortening was observed in LB films.

Effective energy transfer and luminescence of LB films based on europium-substituted heteropolytungstate

The europium-substituted heteropolytungstate K13Eu(SiW11O39)(2) was successfully assembled into two lipids by LB technique for the first time. X-ray diffraction has shown a well defined lamellar for the LB films. The LB films have been characterized by fluorescence spectra and the characteristic luminescence behaviors were discussed. The ligand-metal charge transfer band could be observed in the spectra of the LB films, which could not be found in that of heteropolytungstate solid. The results of fluorescence spectra indicate the energy could be effectively transferred from ligands to the Eu3+ ions in the LB films and the luminescence efficiency was increased greatly. The influences of various lipids on the luminescence of polyoxometalates were investigated. The various interactions between monolayer and polyanions have different effect on the luminescence properties of europium-substituted heteropolytungstate.

Synthesis and characterization of a time-resolved fluorescence analysis chelate reagent-BCPDA

In this paper, we report on a solid phase time-resolved fluorescence immunoassay chelate reagent-4,7-bis(chlorosulfophenyl)1, 10-phenanthroline-2,9-dicarboxylic acid (BCPDA), which is suitable as a fluorescent labeling agent. The five step synthesis product of BCPDA was presented for improving the purity of the product based on the three step synthesis product. The approach involves chlorization, hydrolyzing the ester, preparing disodium, carboxylate to diacid, sulfonation. The yield of five step product is 99 %, 45 %, 94 %, 95 %, 80 % respectively. The structure and purity of product was characterized by the melting point, IR,H-1 NMR, UV spectrum, element analysis, and proved to be consistent with the structure predictal.

Electroluminescence based on a beta-diketonate ternary samarium complex

The triplet energy state of the HTH [HTH: 4,4,5,5,6,6,6-heptafluoro-1-(2-thienyl) hexane-1,3-dione] ligand was measured to be 20 400 cm(-1), which indicated that Sm(HTH)(3) phen (phen: 1,10-phenanthroline) is a good complex to produce strong PL intensity and high fluorescence yield. Electroluminescent (EL) devices using the Sm( HTH) 3 phen complex as the emissive center were fabricated by vapor deposition and spin-coating methods. The relative intensity of the EL spectra changed compared to the photoluminescence (PL) spectrum, which suggested that the luminescence mechanisms of PL and EL have differences. A luminance of 9 cd m(-2) and a higher brightness of 21 cd m(-2) were obtained from the devices ITO/TPD (40 nm)/ Sm( HTH)(3) phen (50 nm)/ PBD (30 nm)/ Al (200 nm) and ITO/PVK (40 nm)/ PVK : Sm( HTH)(3) phen (2.5 wt%, 50 nm)/ PBD (30 nm)/ Al (200 nm), respectively.

Photoluminescent multilayer films based on polyoxometalates

Ultrathin multilayer films consisting of the polyoxotungstoeuropate cluster K-12[EuP5W30O110] (EuP5W30) and poly( allylamine hydrochloride) (PAH) have been prepared by the layer-by-layer self-assembly method. The (EuP5W30 /PAH) multilayer films have been characterized by small-angle X-ray reflectivity measurements, X-ray photoelectron spectra, and atomic force microscopy (AFM). From the AFM images, the thickness of the {PEI/PSS/PAH(EuW30/PAH)} multilayer film was estimated to be 6.5 nm, corresponding to an average thickness of ca. 1.1 nm for a EuW30/PAH layer pair. The photoluminescent behavior of the film at room temperature was investigated to show the characteristic Eu3+ emission pattern of D-5(0)-->F-7(J). The fluorescence behavior of the multilayer film is essentially identical to that of H-n[EuP5W30O110]((12-n)-) in a concentrated aqueous solution, except for the relative intensities and peak bandwidths. The occurence of photoluminescent activity confirms the potential for creating luminescent multilayers with polyoxometalates (see ref. 23).