最新刊期
卷 31 ， 期 3 ， 2010
- 摘要：LiEuW2O8 phosphor was prepared with lithium carbonate, europium oxide and tungsten oxide. The spectral properties and morphology were exhibited by fluorescence spectrometer and SEM, respectively. The result showed that there is a wide excitation spectrum of this phosphor being suitable for LED chips with near-ultraviolet(NUV), blue or green emission. Its emission peak locates at 615 nm, and the emission chromaticity coordinates are x＝0.666,y＝0.331; Milling obviously impacts on its morphology. Sulfide phosphor and LiEuW2O8 phosphor were encapsulated, respectively, to compare their properties, the result showed that the latter can also decrease color temperature, and more importantly,the luminous efficiency is less affected, it can keep 60 lm/W above when color temperature is 4 000 K.关键词：LiEuW2O8;white LED;package;color temperature108|110|3更新时间：2020-08-12
- 摘要：A series of novel red light-emitting phosphors LiGd1-xEu<em>x(MoO4)2 were synthesized by solid-state reaction at high temperature. Their structure and luminescent properties were investigated in detail. The XRD patterns showed that all the phosphors are isostructural and share a tetragonal scheelite structure of space group I41/a88. In the emission spectra of the phosphors, the predominant transition emission is 5D0→7F2 (616 nm) of Eu3+, whereas the other emissions are very weak. The excitation spectra are composed of ligand-to-metal charge transfer bands (CTB) of Mo6+-O2-, as well as a few excitation transitions of Eu3+ between 4f levels. The LiGd0.6Eu0.4(MoO4)2 phosphor shows very strong emission intensity in comparison with commercial phosphor Y2O2S ∶ Eu3+. Although the fluorescence intensity of LiGd0.6Eu0.4(MoO4)2 is slightly lower than that of the LiEu(MoO4)2 , the content over 60% Eu3+ is saved. Therefore, the LiGd0.6Eu0.4(MoO4)2 phosphor significantly reduces the cost of raw materials. It might be a potential candidate for white LED application.关键词：phosphor;molybdate;Eu3+;LED123|125|8更新时间：2020-08-12
- 摘要：The Eu2+-doped silicate based phosphors are very suitable for LEDs. These phosphors show broad emission colors which may vary from near UV to red light through 4f-5d transition of Eu2+ activator and strongly depend on the host lattice, thus the emission wavelength is tunable by modifying the composition and structure of the hosts. This provides a possible way to fabricate color-tunable phosphors for LEDs.In this article, a new composition of color-tunable phosphor material Ba1-xCa<em>xMgSiO4 : Eu2+ doped with Ca2+(x≤0.15)was synthesized by conventional solid-state reaction in a reductive atmosphere(95%N2+5%H2), their luminescent properties and the influence of Ca2+ content were investigated by X-ray diffraction(XRD) and fluorescence spectrometer. The results showed that the emission of the phosphors turns from 498 to 450 nm, when the content of Ca2+ increases in 0~0.05.The maximum emission and excitation intensity are reached when the content of Ca2+ is equals to 0.075, and the shape of the excitation spectra also changes as increasing the content of Ca2+. The XRD curves show that the single phase limit of Ca2+ in the phosphors is below 0.075.The results can be explained by Ca2+ substitution for Ba2+ in different lattice sites and the crystal field strength. As reported by Mingying Peng et al in the structure of BaMgSiO4, there are three different barium sites Ba(1), Ba(2) and Ba(3) with equal amounts in the lattice. The 498 nm emission band corresponds to the Eu2+emission on the Ba(1) and Ba(2) sites. And the two absorption bands at 360 and 400 nm in the excitation spectrum are assigned to the Eu2+centers on Ba(1) and Ba(2) sites, respectively. The Ba2+ at the Ba(2) can be more easily substituted by Ca2+ because of a longer average Ba-O distances . The strength of crystal field around the Eu2+ ion on Ba(1) sites changes when Ca2+ substitutes the Ba2+ at Ba(2),which leads to the change of excitation and emission spectra of the Eu2+ ion on Ba(1) sites. Then, when the content of Ca2+ is over 0.075, Ca2+ at Ba(2) reaches saturation, and the CaMgSiO4 phase occurs. This leads to impurity quenching. Ca2+ substitution for Ba2+ at Ba(1) also causes the change of the excitation spectrum.关键词：Ba1-xCaxMgSiO4 : Eu2+;emission spectrum;excitation spectrum;XRD114|97|1更新时间：2020-08-12
- 摘要：Optical properties of Yb3+/Er3+ co-doped, Ce3+/Yb3+/Er3+ co-doped fluoride phosphate glass and that of Ce3+/Yb3+/Er3+ co-doped fluoride phosphate glass with different content of Al(PO3)3 were stu-died. Based on up-conversion mechanism, energy matching and level, the effect of content of Ce3+ and Al(PO3)3 on the optical properties have been analyzed. The results show that the light changes from green to yellow then to red with the content of Yb3+/Er3+ increasing and keeping the ratio of Yb3+/Er3+ as 4 ∶ 1. And with the introduction of Ce3+ into the glass, non-radiative relaxation takes place from the 4I11/2 to 4I13/2 level of Er3+, which weakens the up-conversion of light to some extent. Phonon energy of energy transfer process of Er3+ and Ce3+ change with changing content of Al(PO)3, and the degree of extinction also changes correspondingly. At the same time, through the mechanism of their up-conversion, we get the photon conversion process of red, green and blue light.关键词：fluorophosphate;up-conversion;rare earth ions102|121|0更新时间：2020-08-12
- 摘要：An efficient hole-injection contact was achieved for organic light-emitting diodes (OLEDs) based on molybdenum oxide (MoO3) as the buffer layer on indium tin oxide. The significant effect of MoO3 is that the devices show low operational voltage and high electroluminescence efficiency in a wide range of MoO3 thickness. The device with a 1 nm-thick MoO3 layer shows the best performance, the current efficiency is enhanced by 1.6 times by comparing with the control device. Capacitance-voltage measurement demonstrated that hole injection is enhanced in low operational voltage through the addition of MoO3. Results of the hole-only devices revealed that ohmic hole injection is formed at ITO/MoO3/NPB interface. Photovoltaic measurements confirmed that the improved hole injection is due to the reduction of barrier height, which is resulted from the addition of transition metal oxide.关键词：OLED;molybdenum oxide;capacitance measurements;ohmic injection;photovoltaic measurements107|123|5更新时间：2020-08-12
- 摘要：Polymer light-emitting devices(PLED) with the structure as ITO/PEDOT ∶ PSS/PVK/Ca ∶ Al were fabricated by spincoating PVK precursor dissolved in different solvent as emitting layer. Meanwhile, those with same structure and varied PVK molecular weight were prepared. In experiment, the peak at 590 nm was found in EL spectra and was assigned to triplet excimer in PVK layer. The intensity of the peak is depend on molecular configuration of PVK, that is on what extent the adjacent carbazole groups overlap in PVK molecule. It was found that the number of the state, that adjacent carbazole groups are completely overlapped increases in PVK molecula after proper UV irradiating. Under this condition, more triplet excitons could are generated and luminance efficiency is improved.关键词：PLED;EL;triplet136|218|1更新时间：2020-08-12
- 摘要：The negative refractive index dielectric (NRID) was introduced into the microcavity organic light-emitting device(MOLEDs). The new microcavity containing negative refractive index dielectric layer(NRIDL) was exhibited. Firstly, the transmission matrix model of the negative refractive index dielectric was presented. Based on the transfer matrix method, the reflectance spectrum, the dependence of EL spectra on cavity thickness were analyzed and discussed. The results showed that the line widths of the spectra of the new MOLED are narrower and all the peaks are enhanced, comparing to the electroluminescence spectra of non-NRIDL device. And then, the luminescence characteristics and EL spectra of the microcavity OLEDs are theoretically studied. The cavity thickness has few effect on the EL spectrum. All the results show that it is a new way to enhance device efficiency, color purity and thinned the thickness of the MOLEDs.关键词：negative refraction index dielectric layer;EL spectra;transfer matrix method;MOLEDs112|227|0更新时间：2020-08-12
- 摘要：To understand the dependence of the quasi-bound level energies Ez and the tunneling lifetime on the magnetic fields B, resonant tunneling in the triple-barrier structure was investigated by using the transfer matrix method. Transmission probability characteristics and the tunneling lifetime in the triple-barrier structure are investigated, respectively. The results showed that the first quasi-bound energy levels E1z increase, while the second quasi-bound energy levels E2z decrease with the increasing of the middle barrier thickness L. The lifetime τ of E1z and E2z is shor-tened with increasing of B and Landau quantum number n, and the effect of L on τ is weak for B=15 and n=15.关键词：resonant tunneling;triple-barrier structure;transfer matrix theory107|189|0更新时间：2020-08-12
- 摘要：ZnSe-related quantum well structures have attracted much interest with regard to their optoelectronic application. They have large optical nonlinearity due to the large exciton binding energy compared with the Ⅲ-Ⅴ compound semiconductors. The ZnSe/ZnS quantum well structure is a promising material for fabricating laser diodes since they have a direct band gap with wide band gap energy up to 3.75 eV at room temperature. The purpose of the present work is to investigate the polaron effects of the exciton in the ZnSe/ZnS parabolic quantum well (PQW). We assume the trial function has a simple form with the variables describing the motion within the quantum well plane separated from those describing the motion along the growth axis. The interaction of the charged particles with bulk longitudinal optical(LO) phonons is considered only, and the energy of the system is obtained by using a variational method developed by Lee, Low and Pines . The results showed that the ground state energy and the binding energy of the exciton with LO-phonon decrease rapidly with increasing the well width L at the beginning, then decreases very slowly with increasing L. In contrast to our previous work, it can be found that the exciton in the ZnSe/ZnS PQWs is more strongly bound than that in the GaAs/Ga1-xAl<em>xAs PQWs.关键词：exciton;polaron;parabolic quantum well121|99|2更新时间：2020-08-12
- 摘要：The Na-Mg co-doped hexagonal wurtzite thin ZnO film with the c-axis (002) preferred orientation were fabricated on lime-glass substrate by sol-gel spin coating method. The phase structural characteristics and surface morphology as well as optical properties were investigated by X-ray diffraction (XRD), scanning electron microscope (SEM), photoluminescence (PL) and transmittance, respectively. The results showed that Na-Mg co-doping is propitious to the ZnO film growth along the c-axis .The crystal size is influenced by the increase amount of Na content. Proved the ultraviolet emission peak at 380 nm is from the recombination luminescence for exciton energy levels, and found that Mg doped ZnO can make band gap increase indeed. The PL spectrum of Na0.04Mg0.2Zn0.76O has only one violet emission peak, and the transmittance and the band-gap of the Na-Mg co-doped ZnO films are decreased with the increasing of Na content.关键词：ZnO thin film;Na-Mg co-doping;sol-gel method;photoluminescence100|274|1更新时间：2020-08-12
- 摘要：ZnO film was deposited on p-type Si(100) substrate by an LP-MOCVD system using DEZ and H2O as zinc and oxygen sources,respectively. The film was cut into pieces and annealed in nitrogen at 900, 1 000, 1 100 ℃, respectively. The XRD, AFM, XPS, I-V and PL properties were investigated. The results indicated that: (1)The crystalline quality of the samples are improved by the raising of annealing temperature, the size of crystal grains is increased; (2)When the annealing temperature increases from 900 ℃ to 1 000 ℃, inten-sity of the UV emission of the samples is enhanced while the emission in visible region declined; When the annealing temperature raises up to 1 100 ℃, the visible emission was suppressed completely and the UV emission is enhanced greatly. These results suggested that annealing at high temperature does not only improve the crystal quality of ZnO films but also controls the Zn/O composition ratio of the samples. A high temperature and nitride environment makes the O atoms escape from the films, the concentration of OZn acceptors decreases, so that the visible emission decline. When the annealing temperature gets higher than 1 000 ℃, the samples are in the Zn-rich state. The UV emission related to the Zni donors is enhanced obviously.101|267|2更新时间：2020-08-12
- 摘要：The electrical and optical aging characteristics of GaN-based light-emitting diodes on Si substrate were studied. The LED samples were stressed at room temperature with an injection current of 200 mA. Light-output power increases in the first stage and decreases with aging time. The current-voltage characteristics were also analyzed. Reverse current and forward current at low bias were increased significantly. The external quantum efficiency (EQE) of device after aging is lower than the pre-aging one. The EQE attenuation before and after aging are significantly different at different injection currents. The smallest attenuation occurs in the current density range corresponding to the highest efficiency.关键词：Si substrate;GaN;blue LED;aging test;luminous decay109|281|2更新时间：2020-08-12
- 摘要：As the surprising development of fiber telecommunication and microelectronics technology, opto-electronic integrated circuit (OEIC) has becomes the focus of advanced research in the world recently. At present, there have been many new technologies that are applied to silicon-based light emission, such as po-rous silicon, nano crystals, SiGe, and so on, because Si material is low cost and the manufacture technology is mature. However, these techniques realize optical interconnection difficultly, which can not be compatible with the mature very large scale integrated circuits (VLSI) technology. One of the key works is to realize a practical light source to satisfy the requirement of optical interconnection. To obtain a Si LED(light-emitting diode) which can transmit optical signal in a chip, it was considered to improve the light intense and decrease cost by using new manufacture technology. In this paper, a forked type of Si LED is designed and manufactured with Singapore Charters 0.35 μm double-grid standard CMOS technology. The device structure adopts n-well and p-sub junction, which n-well is a forked type and is embedded in p-sub. The idea of layout design is to achieve even light of Si LED, because the contact area of n-well and p-sub is large, and the electric field is symmetrical and uniform. At room temperature, the Si LED is reverse biased. The Si LEDs emitting micrographs and real layouts are captured by an Olympus IC microscope, and the I-V characteristics and emission spectra of Si LED are presented. With forward bias, the threshold voltage is 0.9 V. And the Si LED can emit an visible light when the reverse bias is 15 V. Its radiant intensity is 10 nW at 50 mA current and the emitting peak value is located at 758 nm. As it is known, Si is an indirect band gap material, the emission intense of Si LED would be low. But the emission of our Si LED can meet the detect requirement of Si detectors.关键词：silicon;LED;standard CMOS technology107|293|0更新时间：2020-08-12
- 摘要：SiC is an ideal material for manufacturing devices for use in power electronics, high temperature electronics and microwave communication. However, due to its wide band gap, SiC is not sensitive to long-wavelength light ranging from most of the visible to the infrared region of the optical spectrum. This essentially limits its application for detection of visible and infrared light. A promising way to solve this problem is to adopt an SiCGe/SiC heterojunction structure, in which the ternary alloy SiCGe with appropriate composition is used as a light-absorption layer. In this paper, the ternary alloy SiCGe thin films were grown on 6H-SiC substrates in a conventional hot-wall CVD system. The influence of growth temperature on the photoluminescence (PL) and the structure of thin SiCGe films was investigated by PL spectroscopy and scanning electron microscope. The relation between the PL characteristics and structure of thin SiCGe films is discussed. The PL spectra of the thin SiCGe films grown at different growth temperatures (980,1 030 and 1 060 ℃) exhibit emission peaks located at 2.13,2.18,2.31 eV, respectively. The component analysis and band-gap calculation of thin SiCGe films showed the PL peak comes from the radiative recombination between energy bands. And the regulatory effect of changing growth temperature on band gap of the thin SiCGe films is confirmed. The tempe-rature-dependent PL spectra showed that the peak has an obvious blue-shift when the testing temperature increases higher than 200 K. It is due to different luminescent mechanisms. When the testing temperature is under 200 K, photoluminescence is related to the impurity and defect energy levels; as the testing temperature is higher, the radiative recombination is dominant in the luminescent mechanisms.关键词：SiCGe;LPCVD;growth temperature;photoluminescence89|192|1更新时间：2020-08-12
- 摘要：Both Er3+and Er3+-Yb3+ codoped CaWO4 nanocrystalline were prepared by chemical co-precipita-tion method. We characted the crystal structures and the room temperature down-conversion emission and up-conversion emission properties of samples with different doping concentrations of Er3+ and sintered at different temperatures, respectively. By comparing the influence of different sintering temperatures and doped concentrations on the characteristic emission of Er3+ , it was found that the emission intensity depends on the sintering temperature. The emission intensity increases as the sintering temperature increasing. The effect of the concentration of doped Er3+ on the fluorescence emission intensity shows that the optimum concentration for the luminescence of Er3+ is 0.6％. The energy transfer was observed between the charge transfer state of O-W and the rare earth ion Er3+ , and a model for explaining the energy transfer was given. By studing the upconversion emission of Er3+ , it was showed that the Yb3+ can promote the upconversion emission of Er3+ under 976 nm excitation by the resonance energy transfer.关键词：nanocrystalline CaWO4 ∶ Er3+;chemical co-precipitation;photoluminescence;up-conversion emission104|65|3更新时间：2020-08-12
- 摘要：GdVO4 ∶ Eu3+ luminescent nanomaterials with different morphologies were prepared by hydrothermal method, and their structure and luminescent properties were characterized. XRD patterns showed that the precursors and the heat-treated samples are tetragonal phase GdVO4 crystals. TEM images indicated that the rice-shaped, tetragonal-shaped and spherical GdVO4 ∶ Eu3+ nanoparticles were obtained by changing different surfactant. Fluorescence spectra showed that under the excitation of 288 nm, GdVO4 ∶ Eu3+ nanomaterials with different morphologies have the characteristics of red emission in 617nm, attributing to the 5D0→7F2 transition of Eu3+, the intensities of the fluorescence spectra are different for different samples prepared with different surfactants.关键词：GdVO4 ∶ Eu3+;nanocrystal;hydrothermal method100|111|3更新时间：2020-08-12
- 摘要：Self-assembly of rod-like SiOx(x=1~2) nanostructures were formed via chemical vapor deposition method by heating the Mg2Si and SiO2 nanoparticles mixture at low temperature. The nanostructures were analyzed by scanning electron microscopy, transmission electron microscopy, energy dispersive spectroscopy and low-energy electron diffraction methods. The photoluminescence (PL) characterization spectrum of the nanostructures showed a strong peak at 560 nm. Furthermore, the growth mechanism of the SiOx nanostructures was discussed qualitatively.关键词：Si;SiOx;nanostructure;self-assembly;optical property119|79|0更新时间：2020-08-12
- 摘要：In this paper a ratiometric fluorescence nanogel was prepared and used in pH sensing. By introducing a pH probe and two fluorescent dyes (related by fluorescent resonant energy transfer), the non-responsive and non-fluorescent hydrogel (polyurathane) was imparted the ability of pH sensing. With the increase of pH value from acidic to basic, the dominant fluorescence of nanogels varieds from red to green accordingly. The as-prepared nanogels exhibits high sensitivity, high hydrophilicity, quick responsiveness, and physiological pH detecting in the range of 6~8. Hence, the nanogels would be very potential as intracellular pH nanosensors.关键词：nanogel;pH sensor;ratiometric fluorescence;FRET140|198|2更新时间：2020-08-12
- 摘要：a-C ∶ N ∶ H nanotips were fabricated on the Si substrate deposited with carbon film by plasma-enhanced chemical vapor deposition using methane, hydrogen and ammonia as the reaction gases. The carbon film and the nanotips were characterized by scanning electron microscopy and micro-Raman spectroscopy and the results indicated that the Raman spectra have the peaks related to carbon and nitrogen and the photoluminescence background in the Raman spectrum of the carbon nanotips is stronger than that of the carbon film. The peaks in the Raman spectra illustrates that the deposited carbon film and the nanotips are a-C ∶ N ∶ H film and a-C ∶ N ∶ H nanotips, respectively. The strong photoluminescence background in the Raman spectrum of the a-C ∶ N ∶ H nanotips indicates that the a-C ∶ N ∶ H nanotips produce the strong photoluminescence when the a-C ∶ N ∶ H nanotips are irradiated by the excitation of 514.5 nm Ar laser. The mechanism which the a-C ∶ N ∶ H nanotips produce strong photoluminescence was analyzed.关键词：a-C ∶ N ∶ H nanotips;Raman spectrum;photoluminescence114|103|0更新时间：2020-08-12
- 摘要：A series of Y3+-doped terbium complexes with phenoxyacetic acid and 1, 10-phenanthroline were synthesized in anhydrous alcohol. Elemental analysis and rare earth complexometic titration showed that the composition of the complexes are TbxY1-x (POA)3phen·1/2H2O(POA=C6H5OCH2COO-, x=1.0,0.9, 0.8,0.7,0.6,0.5,0.4,0.3,0.2 and 0.1). The IR absorption spectra indicated that the rare earth ions are bounded with the oxygen atoms of phenoxyacetic acid and phenoxy, and with two nitrogen atoms of 1,10-phenanthroline. Thermogram and thermogravimetric analysis indicated that the complexes release coordinated water at about 274 ℃ and they are stable below 576 ℃. Fluorescent spectra showed that the fluorescence intensity of the series Tb3+ complexes can be greatly enhanced if some of terbium ions in the complexes are substituted by Y3+. The fluorescence lifetime of the complexes exhibits the similar feature to the fluorescence intensities.116|78|1更新时间：2020-08-12
- 摘要：Europium (Ⅲ) chelate nanoparticles (NPs) were prepared and surface functionalized to detect Cu ( Ⅰ ) ions. The detection mechanism is based upon 1,3 dipolar cycloaddition of alkynyl groups to azido groups being able to be catalyzed by Cu( Ⅰ ), through which a fluorescent resonance energy transfer (FRET) system is constructed between NP and an acceptor fluorescent dye. By monitoring the fluorescence of the acceptor dye, the concentration of Cu ( Ⅰ ) ions was reported since the speed of click reaction is proportional to its concentration. Owing to the smart detecting scheme, Cu( Ⅰ ) ions (in micromolar concentrations) can be detected.关键词：Eu3+ chelate nanoparticles;Cu ( Ⅰ ) ion;fluorescence detection;click reaction;fluorescent resonance energy transfer103|118|0更新时间：2020-08-12
- 摘要：In this paper, the influences of electron donating and withdrawing substituents on photoelectric properties of 8-hydroxyquinoline lithium (Liq) are systematically studied by density functional theory (DFT), several significant research results were achieved to provide theoretical guidance for further improving the performance of Liq. The research results showed that the different substituents form different conjugate with the parent population. The substituents of —CN, —OCH3 participate in the π-conjugated system properly, and have a great influence on the properties of the system. While the substituents of —CF3, —CH3, —CH3CH2CH2, —Cl have the weaker conjugated effects with the system, and relatively a little influence on the properties of the system is obtained. The electron donating substituents enhance O-Li electrostatic interaction and N-Li covalency, and the electron withdrawing substituents weaken O-Li electrostatic interaction and N-Li covalency. The electron withdrawing groups of —CF3, —CN, —Cl,which is attached to 5-position of Liq, make LUMO and HOMO energy level lower, but the dependence of the LUMO, HOMO and band gap on their inductive effect strength lack regularity. The —CF3, —CN broadens band gap of Liq, however the —Cl leads to band gap of Liq reducing. Here, the synergistic action of conjugated effects should be included. The electron donating groups of —CH3, —CH3CH2CH2, —OCH3 which is attached to 5- position of Liq, make LUMO and HOMO energy level rise and band gap contract, the stronger interaction between the substituent and the molecular orbital, the more remarkable the influence on the frontier molecular orbital. The —CN substitution at 5-position of Liq make the electron affinity significant increase, thereorganization energy decrease, so that electron injection and transport become more easy. It can be concluded that 5-CN-Liq is a kind of better electron injection and transport materials than Liq and other derivatives of Liq.关键词：density functional theory;8-hydroxyquinoline lithium;substituent effect;photoelectric properties119|268|0更新时间：2020-08-12
- 摘要：Nanoporous metal-organic frameworks (MOFs) materials have been developed rapidly in recent years. The materials were constructed of organic ligands and metal ions. Multi-functional MOFs materials were designed by different organic ligands and metal ions, i.e. Zn2+ and 1,4-benzenedicarboxylic acid (H2BDC) can assembled to 1-D,2-D,3-D MOFs materials. They can be applied in gas storage,chiral separation,catalysis,molecular magnet and photoelectric material. However, only a few examples of porous MOFs with open metal sites have been illustrated for their functional properties, mainly because of the difficulty of constructing robust MOFs that hold open metal sites.In this paper, H2BDC and Zn2+ are chosen to synthesize 1-D MOF by using precipitation method, which is a facile and environmentally friend method. A series of coordination polymers, i.e. , were obtained by substitution and adsorption in the reaction of with different content of 8-hydroxyquinoline. Their structures were characterized by XRD and FT-IR . The results of XRD show no structure change in low content of 8-hydroxyquinoline. How-ever, when n(8-Hq) ∶ n( )=1 ∶ 20, the peaks of XRD have obviously difference to standard chart. It may be attribute to 8-Hq substituting coordination water. When n(8-Hq) ∶ n( )﹥1 ∶ 1, coordination water was substituted whole, and the adsorption effects is dominant. TEM images showed nanocrystals of are grown with increase of 8-Hq concentration.Nanocrystals of and exhibit strong solid state fluorescence properties. Fluorescence emission spectra revealed that the wavelength of maximum emission (λem) redshifts regularly with increasing the amounts of 8-hydroxyquinoline, λem redshifts from 376 nm to 428 nm with n(8-Hq) ∶ n( )=1 ∶ 200~1 ∶ 80. Changing the ratio of n(8-Hq) ∶ n =4 ∶ 1, λem redshifts to 528 nm. These phenomena were explained rationally by fluorescence area integral. The results suggest that emission spectrum can be tuned by varying ratio of to 8-hydroxyquinoline. These kind of metal-organic frameworks have potential applications for display devices, fluorescence imaging, and fluorescence label, and so on.关键词：metal-organic frameworks;8-hydroxyquinoline;nanocrystals;fluorescence109|145|2更新时间：2020-08-12
- 摘要：A fluorescent and conductive composite material was formed by doping Eu-containing hydrotalcite-like compound in the polyaniline.The structure and properties have been characterized with electrical conductivity methods, fluorescence spectrum, FT-IR techniques, X-ray diffraction (XRD) and thermogravimetric analysis(TG).The results showed that the composite material was a semiconductor material which had good fluorescence propertics.Otherwise,the composite material had better thermal stability than the relevant PAN-CSA.The composite material may become a promising candidate for new fluorescent materials.关键词：hydrotalcite-like compound;polyaniline;fluorescence;composite material108|281|0更新时间：2020-08-12
- 摘要：By combining 7-diethylamino-2-oxo-2H-chromene-3-carbohydrazide with 2-pyridylaldehyde into one molecule,fluorescent probe XB was synthesized for detection of Cu2+ in aqueous solution V(CH3CN) ∶ V(H2O)=1 ∶ 1). The probe is highly selective for Cu2+ over biologically relevant alkali metals, alkaline earth metals and the first row transition metals such as Cr3+,Mn2+,Fe3+,Co2+,Ni2+,Zn2+,Cd2+ and Hg2+. Spectrophotometric titration and ESI-MS spectra indicate the formation of a 1 ∶ 2 complex of Cu2+ with XB.关键词：fluorescent probe;Cu2＋;coumarin;chemosensor100|150|5更新时间：2020-08-12
- 摘要：By means of the transfer matrix method, transmission spectra characteristics of single-negative materials with one-dimensional photonic crystal (AB)m(ADBDB)n(AB)mA was researched, and the results showed that the location and space of two resonant tunneling modes can be adjustably controlled by the number of period m or n, and the thickness d of medium layers. Changing m, two resonant tunneling modes of constant space show up; changing dA, the space of them increases, and the space increases more severely when dA≥25 mm;changing n, the two resonant tunneling modes tend to degenerate and become one unit when n≥6; changing dD, they tend to degenerate and become one unit when dD≥20 mm. These characteristics can provide references for designing the adjustable high-quality single-channel and double-channel filters.关键词：single-negative materials;transfer matrix;resonant tunneling modes;filter112|153|7更新时间：2020-08-12
- 摘要：Transmission properties of photonic crystal heterostructure consisting of negative materials was stu-died by transfer matrix. The results showed that, as the incident wave at normal incidence, not only a photo-nic gap appears in this kind of photonic crystal heterostructure but also three very narrow transmission peaks appear in this gap. The positive and negative alternating one-dimensional photonic crystal and the same periods of one-dimensional heterostructure photonic crystal, which consists of conventional materials, dont have this characteristic. Transmission spectrum of this kind of photonic crystal was calculated.It was found that the three transmission peaks are insensitive to the angle of incidence, but the transmission peaks on both sides of the gap will move to the gap with the increasing of the incident angles.The energy band is sensitive to the scale length of crystal lattice and the change of the periods number.关键词：photonic crystal;negative materials;transfer matrix98|113|2更新时间：2020-08-12
- 摘要：Dispersion and nonlinearity are the main adverse factor in modern long-distance and high bit-rate optical transmission systems. Recently, the dual-concentric-core structures, used in conventional dispersion compensation fibers have also been adopted in the design of photonic crystal fibers (PCFs). Large negative dispersion is always associated with small effective area, which leads to undesirable nonlinear effects during optical signal transmission. By employing the vectorial beam propagation method, a novel dual-core photonic crystal fiber based on pure silica for broadband dispersion compensation with low nonlinearity was proposed. The influence of the air-filing fraction in cladding and the distance between the inner and outer cores on the dispersion and nonlinear coefficient was numerically investigated. The simulation results showed that, by introducing the outer core by removing one air-hole ring in the cladding and adjusting the distance between the inner and outer cores and the air-filing fraction, the mode coupling of the inner and outer cores can take place in a wide wavelength range, which can induce larger negative dispersion. Meanwhile, since the light field is distributed in the two cores, the effective mode field area is larger so that the nonlinear coefficient is lower. These simulation results will be useful for designing broadband dispersion compensation fibers with low nonlinearity.关键词：fiber optics;photonic crystal fiber;vectorial beam propagation method;dispersion;nonlinearity111|104|0更新时间：2020-08-12
- 摘要：The problem included in the crystalline undulator field radiation is complex and more the free electron laser because of the dechanneling effect by the crystal bend,the electron multi-scattering and the thermal oscillation of the lattice, the ionization loss by an interaction between the radiation with an atom, the global bifurcation and the chaotic behaviours by the nonlinearity of the system,etc. Firstly, the introducing the spectral distribution of a spontaneous radiation for the crystalline undulator field based on the classical field theory, the particle motion equation,the gain factor and the radiation attenuation were discussed in a harmoric approximation. The results showed that there is few radiation lines in the general case; and there is only one line in a harmoric approximation. Secondly, it was pointed out that the radiation attenuation is major if energy is higher, then the crystal length must be selected smaller than the dechanneling length, and one may selects a positron or a proton as projectile; in addition, the dechanneling effect is major if energy is lower, then the crystal length must be selected smaller than the attenuation length, and one may select a heavy ion as projectile.关键词：crystalline undulator radiation;spectral distribution;gain factor;radiation attenuation120|100|6更新时间：2020-08-12
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