最新刊期
卷 32 ， 期 2 ， 2011
- 摘要：The Ca4Y6O(SiO4)6 ∶ Dy3+ phosphor was synthesized by high temperature solid state reaction, and the luminescent properties were investigated. The XRD patterns indicated that the phosphor of Ca4Y6O(SiO4)6 ∶ Dy3+ was pure crystalline phase. The study on the luminescent properties showed that the phosphor exhibits two emission bands centering at 480 nm and 573 nm. The excitation spectra for blue emission (480 nm) and yellow emission (573 nm) both have several sharp peaks, locating at 293,323,348,363,386,424,452 nm, which are assigned to the typical transitions of Dy3+ . The strongest peak appears at 348 nm. The influence of the doped concentration of Dy3+ on the ratio of yellow to blue emission intensity (IY/IB), with the emission color coordinates and color temperature of phosphor Ca4Y6O(SiO4)6 ∶ Dy3+ were studied. The effect of Dy3+ concentration on the luminescence and the quen-ching mechanism according to the Dexter theory were also analyzed.关键词：phosphors;luminescent properties;quenching;Ca4Y6O(SiO4)6 ∶ Dy3+107|75|3更新时间：2020-08-12
- 摘要：In the framework of effective mass approximation, a variational method is adopted to discuss the binding energies of hydrogenic impurity in a strained wurtzite cylindrical quantum dot by considering the hydrostatic pressure. The results indicate that the binding energies of hydrogenic impurity with strain effect are higher than that without strain effect when the quantum dot height is small, but the binding energies with strain effect become lower than that without strain effect as the quantum dot height increases. It is also found that the binding energies of hydrogenic impurity decrease when the mole fraction of Al increase. In addition, the bin-ding energies of impurity increase obviously with hydrostatic pressure, and the hydrostatic pressure has a remarkable influence on the donor binding energy for small quantum dot.关键词：quantum dot;hydrogenic impurity;strain;hydrostatic pressure103|119|1更新时间：2020-08-12
- 摘要：In this paper, red afterglow phosphor Y2O2S ∶ Eu,Mg,Ti,Gd was prepared by solid state reaction method and the thermal stability was studied in detail. The obtained phosphor compositions were characterized by X-ray diffraction (XRD). Luminescent properties were investigated by measuring emission spectra, excitation spectra and decay curves. When the heating temperature rises from 200 to 600 ℃, the major phase is Y2O2S and the luminescent properties are almost unchanged. When the heating temperature is 800 ℃, the Y2O2SO4 and Y2O3 phase are observed. The peak position and peak pattern of emission spectrum are unchanged, but the intensity of emission spectrum is decreased. The excitation spectrum shows the same variation regularity. The relative intensity at 5 min (after the excitation source was turn off) is decreased to 80% compared with the one without heating process. When the heating temperature is increased to 1 000 ℃, the major phase is changed to Y2O2SO4 and Y2O3, the intensity of emission spectrum is very low. The afterglow phenomenon almost disappears. The thermal stability of Y2O2S ∶ Eu,Mg,Ti,Gd phosphor is better than that of sulfide and aluminates phosphors. Thus, the Y2O2S ∶ Eu,Mg,Ti,Gd phosphor is a promising candidate of red afterglow luminescent material which can resistant to higher temperature environment.关键词：long afterglow;oxsulfide;thermal stability;luminescent material117|125|1更新时间：2020-08-12
- 摘要：Four novel bis-Schiff base ligands and their zinc(Ⅱ) coordination polymers were synthesized from the bisalicylaldehydes based on the backbone of bisphenol A. The structures, thermal stabilities, luminescent properties and energy bands were investigated by infrared spectra, 1H NMR, TG curve, UV-Vis absorption spectra and fluorescence emission spectra. The results showed that these complexes are thermally stable with high decomposition temperature at 405 ~443 ℃. The complexes emit blue-green fluorescence with the maximum emission peaks at 493 ~503 nm. Their quantum yields are close to that of the repoted literatures, the band gap is about 3.04 ~3.23 eV. The results above suggest that the novel coordination ploymers can be utilized as good organic electroluminescent materials.关键词：bisalicylaldehyde;Schiff base;coordination polymers;fluorescence109|138|1更新时间：2020-08-12
- 摘要：In this paper, a complex of rare earth europium (Eu) with Undecylenic acid (UA) was synthesized. Then the Eu-UA-siloxane composite was hydrosilylated from polyhydrosiloxane and the complex at the presence of Pt-catalyst, and characterized by means of FT-IR and 1H-NMR. The fluorescence spectra demonstrated that the composite was excited with a wavelength of 393 nm,exhibited the strongest emission at 616 nm. The fluorescence intensity of the composite increase linearly with the contents of europium increasing, no concentration quenching phenomenon was found.关键词：complex;polyhydrosiloxane;hydrosilation;fluorescence92|140|0更新时间：2020-08-12
- 摘要：Eu3+-doped NaGdTiO4 red phosphors were synthesized by conventional solid state reaction method. The effects of TiO2 content and Eu3+ mole fraction on the crystal structure and photoluminescence properties were investigated by X-ray diffraction and fluorescent spectra. The XRD patterns showed that the resultants with single orthogonal phase structure were achieved when TiO2 content increased by 50% on the basis of stoichiometric reaction composition. In the excitation spectra of single orthogonal structure NaGdTiO4 ∶ Eu3+ phosphors, by monitoring 618 nm, the charge transfer bands (CTB) of Eu3+ -O2- and NaGdTiO4 matrix absorption centered at around 250 nm and 281 nm were observed, respectively. Under 281 nm excitation, strong red emission was observed at 618 nm originating from the 5D0→7F2 electric dipole transition of Eu3+ , which suggests that there exist effective energy transfer from NaGdTiO4 matrix to Eu3+. The calculated emission color coordinates of NaGdTiO4 ∶ 20% Eu3+ are x=0.63, y=0.34. These results show that NaGdTiO4 ∶ Eu3+ phosphors might have potential applications in whit light-emitting diodes (LEDs).关键词：NaGdTiO4 ∶ Eu3+;red phosphor;white LEDs111|87|4更新时间：2020-08-12
- 摘要：Zn2SiO4(ZnB2O4) ∶ Mn2+ ,Sm3+ phosphors was fabricated by solid reaction method. The influences of sintered temperature and Sm3+ content on the luminescence properties of Zn2SiO4(ZnB2O4) ∶ Mn2+ ,Sm3+ phosphors were studied. Powder structure and luminescence properties were characterized by means of XRD, excitation and emission spectra. The experimental results indicate that Zn2SiO4(ZnB2O4) ∶ Mn2+ ,Sm3+ has two excitation peaks at 220 nm and 250 nm, the luminescence intensity is the largest when the sintered temperature is at 950 ℃ in reducing atmosphere, and the emission peaks at 521 nm. The ZnB2O4 as a part of host produced in the reaction can improve the luminescence intensity. At 950 ℃,there are most ZnB2O4 reaction products, meanwhile, ZnB2O4 has the best crystalline properties. With the Sm3+ content increased, the phase is not changed, however, to a large extent, the luminescence intensity can be improved. When the Sm3+ mole fraction is 8%, the intensity is the most and 5 times stronger than that for 4% Sm3+. With the increasing of Sm3+ mole fraction, the luminescence emission peak has blue-shift from 540 nm to 521 nm.关键词：Zn2SiO4(ZnB2O4) ∶ Mn2+;Sm3+;phosphors;sintered temperature;Sm3+ content112|81|0更新时间：2020-08-12
- 摘要：During the recent decades years, the luminescence properties of divalent europium have attracted more and more interest for its wide emission spectrum ranging from blue to blue-green. As for the rare earth optical glasses, the rare earth ion dopants with high brightness and stable performance are always the important point, and Eu2+ doped borosilicate glasses also have these properties.Herein, by using the high-temperature solid-phase synthesis method, a typical blue borosilicate glass named MgO·SiO2·B2O3 ∶ Eu2+ was synthesized. The influence of different Eu2+ doped concentrations on the luminescent properties of borosilicate glass was studied. X-ray diffraction and luminescence spectroscopy were used to characterize this glass samples. Excited by the UV light, the emission spectrum of the glass phosphor consists of two bands, peaking at about 460 nm and 500 nm, which are attributed to the covalence property of the Eu—O bond and the different coordination environments around the Eu2+ ions in the host lattice. The energy transfer process is accompanied by the loss of energy. In addition, with the concentration of divalent europium ions increasing, fluorescence quen-ching occurred,so emission intensity of the 500 nm emission band is weaken.The glass phosphor has strong excitation at around 300~440 nm and emitted a typical bright blue luminescence. And with the mole fraction of doped Eu2+ increasing, the peak of emission spectrum shows a red shift, and the intensity remarkably decreased. Thus it could have applications as a blue component in solid-state lighting devices assembled by near-UV light emitting diodes (LED) and with tricolor phosphors.关键词：blue emissioin;rare earth;borasilicate glass119|211|1更新时间：2020-08-12
- 摘要：The ZnO nanowires were grown on Si(100) substrates by chemical vapor deposition method without using catalyst. The X-ray diffraction (XRD) indicates the highly preferred crystal orientation along the c axis of ZnO in this sample. Field emission scanning electron microscope(FE-SEM) showed well-aligned ZnO nanowires with uniform diameter, length, and density were grown perpendicularly on Si substrate. The top and root diameter of the ZnO nanowires are about 70 nm and 100 nm, respectively, and the length of the nanowires is about 1.5 μm. Furthermore, the As elements were detected in the arsenic doped ZnO nanowires by the energy-dispersive X-ray spectroscopy (EDS). The arsenic related acceptor emission was observed in the photoluminescence spectra at 11 K for all arsenic doped ZnO samples. This preparation method of arsenic doped ZnO nanowires may provide a new way for realizing the ZnO nanowires based light emitting diode and laser diode.关键词：arsenic doped;ZnO nanowires;chemical vapor deposition;photoluminescence109|169|1更新时间：2020-08-12
- 摘要：A novel high-power single-frequency narrow linewidth fiber laser with long linear laser cavity is designed and manufactured by using nonlinear two-wave mixing. The distributed gain gratings and refractive index gratings, which are generated by interfering between the feedback injecting light from the part of output light and the lasing light in intra-cavity, are used to select longitudinal modes efficiently and ensure stable single-frequency operation. A segment Er3+/Yb3+ co-doped double cladding fiber is used as gain medium and is pumped by multi-modes laser diodes (LD) with wavelength of 975 nm, and then stable high-power single-frequency laser at 1 550.63 nm is acquired. The fiber laser exhibits a 356 mW threshold and laser output power is 653.7 mW for a pump power of 3.1 W. Optical-optical efficiency is 21.1%, slope efficiency is 24.6% and signal-to-noise ratio (SNR) is large than 50 dB. The 3 dB linewidth of the fiber laser is about 5.0 kHz, which is measured by the delayed self-heterodyne method with 40 km delayed fiber.关键词：laser optics;fiber laser;two-wave mixing;single-frequency;narrow linewidth126|154|2更新时间：2020-08-12
- 摘要：The variable-temperature photoluminescence (PL) spectra of In0.182Ga0.818As/GaAs strained and strain-compensation quantum wells (QWs) were experimentally determined in the temperature range of 77~300 K. The PL peak positions shift to lower energies with the increasing temperature. Strain which is induced by lattice mismatch between epitaxial layer and substrate removes the degeneracy between the light-hole and heavy-hole states at the top of the valence band. A theoretical calculation was presented that takes into account the temperature-induced variations in band gap and biaxial strain to explain the PL spectra.Based on the Varshni relationship, the change of the band gap energy caused by the strain was introduced. It is the function of the temperature and the alloy composition. The calculated results are agree with the experimental data. The full-width at half-maximum (FWHM) of PL spectra of In0.182Ga0.818As/GaAs strained three quantum wells is larger than that of strain-compensation one, and increases more quickly, which is caused by exciton-LO phonon coupling. At last, strain effect on the PL spectra was confirmed through the FWHM curve at various temperature.关键词：MBE;InGaAs/GaAs;strained quantum wells;variable-temperature photoluminescence104|164|1更新时间：2020-08-12
- 摘要：Photonics crystal (PhC)is the material in which the refractive index changes periodically and the PhC has a band structure and location mode, this structure can control light.In order to study two-dimensional PhC complete band gap,in this paper, plane wave expansion method was employed to simulate four types of two-dimensional PhC. We study the relationship between the complete bandgap and the variation of column radius r with a fixed lattice constant. We found that hexagonal lattice PhC air holes complete band gap appears in the r=0.42~0.50 μm range, complete band gap width does not increase with the air column radiu r, but there is a maximum width. The maximum band gap width is Δω1=0.08(ωa/2πc).When air column radiu r=0.47~0.50 μm,square lattice PhC exists complete bandgap, the band gap width Δω2=0.02(ωa/2πc).And complete band gap center frequency increases with r. Results indicate that for hexagonal and square GaAs columnar PhC there is no complete band gap.关键词：photonic crystal;plane wave expansion method;complete band gap126|116|3更新时间：2020-08-12
- 摘要：In the rotating wave and slowly varying envelope approximations, the density-matrix motion equations for the three-level cascade system equation are solved under the influence of driving-field phase diffusion. The exact linear analytical solutions of the three-level cascade system with the driving field having the phase fluctuation in the steady state are obtained. The effects of phase diffusion on absorption, dispersion and population difference in a three-level upper-ladder system and on the time of steady-state limit in the course of time evolution have been analyzed by using the numerical simulation from the steady linear, analytical solution and density-matrix motion equations. Gain of the probe field will be decreased due to the driving-field phase diffusion. The presence of the finite linewidth induced by the driving-field phase diffusion prevents the ladder system from obtaining a high refractive index along with zero absorption. Variation of the linewidth can not change the property of the lasing in the upper-ladder system. The linewidth as a result of the driving-field phase diffusion has influence to the time of steady state limit and the phase diffusion leads to a decay of the coherence in the course of time evolution.关键词：laser physics;phase diffusion;ladder system103|102|0更新时间：2020-08-12
- 摘要：Photonic crystal fibers with modified honeycomb lattice structure were proposed by combining the advantages of honeycomb lattice and lattice with different air-hole diameters. The dispersive and nonlinear properties of the proposed fibers, which formed by different structural parameters, are numerically simulated by using the vectorial beam propagation method, and the relationship of dispersion, nonlinear coefficient with the lattice structure was investigated. The results indicate that the distinct dispersive properties, which contain large negative dispersion, flattened dispersion, positive dispersion, and so on are achieved in the wavelength range of 1.2~1.6 μm. Furthermore, the decrease of the diameters of air-holes in the lattice structure leads to an increase of effective area in fundamental mode which make the nonlinear coefficient lower. Thus the dispersive and nonlinear properties of the proposed fiber can be flexibly tailored by adjusting its structural parameters. This provides a reference for designing novel photonic crystal fibers.关键词：fiber optics;photonic crystal fiber;dispersion;nonlinearity112|99|0更新时间：2020-08-12
- 摘要：Thermal-resistor of different chips based on C-mount package have been measured with the method of wavelength shift in this paper.Through the thermal-resistance measurement, we can get the best size of chip and the thickness of In solder to make the smallest thermal-resistance. The results show that when the thickness of In solder is 10 μm, the output power is 2 W, the bar width is 200 μm, the cavity length is 2 000 μm and the minimum thermal-resistor of the chip is 2.01 ℃/W.The thermal-resistors with carvity length of 2 000 μs have been measured when the In solder thickness is 5 μm and 10 μm. The results show that the thermal-resistor dropes from 2.01 ℃/W to 1.85 ℃/W for the 5 μm In solider.关键词：thermal-resistor;C-mount package;laser diode;In-solder105|135|6更新时间：2020-08-12
- 摘要：Bottom-gate ZnO thin-film transistors (ZnO-TFTs) were fabricated with Ta2O5 film as the insulator. Ta2O5 film was grown by the radio-frequency magnetron sputtering at room temperature. The thickness of the Ta2O5 layers were 100,85,60,40 nm separately. The effect of the thickness on the performance of the ZnO-TFTs was studied. With the thickness of the insulator decreased from 100,85,60 nm to 40 nm, the field effect mobility increased from 50.5, 59.3, 63.8 to 71.2 cm2/V·s. The surface morphology of the Ta2O5 films were checked by the atomic force microscope,which showed that the root mean square (RMS) of the Ta2O5 films roughness decreases with decreasing the insulator thickness. The Ion/Ioff ratio and the threshold voltage are changed with the insulator thickness.关键词：Ta2O5 insulator;ZnO-TFT;RF magnetron sputtering;surface morphology119|75|5更新时间：2020-08-12
- 摘要：In alkaline condition(pH=9~10), a weak chemiluminescence signal was produced when H2O2 was injected into morin solution, and the chemiluminescence signal could be greatly enhanced after the introduction of cetyl trimethyl ammonium bromide(CTMAB) and sulfide. Based on the observation, H2O2-morin-CTMAB chemiluminescence system has been developed for the determination of sulfide. The possible mechanism of chemiluminescence reaction has also been discussed. Under the optimized conditions, the chemiluminescence intensity of the system presented a linear relationship with the concentration of sulfide in the range of (0.9~9.0)×10-8 g/mL, the linear dynamic equation was ΔICL=49.41+3.3612CS with correlation coefficient of 0.999 0. The detection limit (S/N=3) was 1.2×10-9 g/mL. The relative standard deviations(RSD) was 2.5％ for 8.0×10-8 g/mL sulfide solution. The proposed method was successfully applied to the determination of sulfide in environmental water samples with recoveries in the range of 95.5%~101.3%.关键词：chemiluminescence;morin;hydrogen peroxide;sulfide119|141|1更新时间：2020-08-12
- 摘要：The scattering spectra of high triglycerides, high cholesterol, high blood sugar and normal serum were researched with Shimadzu RF-5301 fluorescence spectrophotometer, and the scattering spectra of serums with same biochemical parameters. The scattering spectra of abnormal serums, such as the serums with hyperlipidemia and the serums with hyperglycemia, have obvious differences from the spectra of normal serums at the characteristic peaks. This result has laid the foundation of distinguishing between normal and high blood sugar, high blood lipids serum. The peak intensity of scattering spectra in the same biochemical markers of different concentrations serum increased with the blood lipids, blood glucose concentrations.Moreover, the peak intensity ratio of I446/I464 and I615/I628 increased with blood sugar concentration, and has a nearly linear relationship. However, there is no similar phenomenon in the scattering spectra of serums with hyperlipidemia. Hence, it can be used to distinguish between the serums with hyperglycemia and the serums with hyperlipidemia. This study provides an experimental basis for clinical application.关键词：resonance scattering spectroscopic;serum;hyperglycemia;triglyceride;high cholesterol115|130|1更新时间：2020-08-12
- 摘要：The interaction of rare earth La (Ⅲ) and Nd (Ⅲ) with BSA were studied by ultraviolet spectrum,fluorescence spectrum and IR spectrum. The results showed that the ultraviolet absorption intensity of BSA increases with the concentration of rare earth. Rare earth can strongly quench the fluorescence of BSA which is the static quenching. The binding constant (KA) of La (Ⅲ) or Nd (Ⅲ) with BSA at room temperature are 8.12×106 and 3.85×106, respectively.关键词：rare earth;bovine serum albumin;ultraviolet spectrum;IR spectrum;fluorescence spectrum112|104|7更新时间：2020-08-12
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