最新刊期
卷 37 ， 期 8 ， 2016
- 摘要：Three luminescence materials, 3-(dicyanomethylene)-5,5-dimethyl-1-styryl-cyclohexene (DCDSC), 3-(dicyanomethylene)-5,5-dimethyl-1-(3-hydroxy-styryl)cyclohexene(DCDH3C) and 3-(dicyanomethylene)-5,5-dimethyl-1-(4-hydroxy-styryl)cyclohexene (DCDH4C), were designed and synthesized, respectively. These compounds were confirmed by 1H NMR and elemental analysis, and their crystal structures were confirmed by single-crystal X-ray diffraction (XRD). UV-Vis absorption peaks of DCDSC, DCDH3C and DCDH4C materials in THF solutions in turns are at about 268 and 390 nm, 269 and 398 nm, as well as 283 and 424 nm. Their maximum emission peaks are at 522, 549 and 567 nm in liquid state, respectively, which may be mainly ascribed to difference between their hydrogen bond besides substituent effect.关键词：isophorone;luminescence;substituent group;hydrogen bond120|147|0更新时间：2020-08-12
- 摘要：Samarium pyrazine-2,3,5,6-tetracarboxylate coordination polymers with sub-micron ellipsoid-like architecture were successfully synthesized via an efficient direct precipitation method at room temperature. Fourier transform infrared spectra, energy dispersive spectrum, scanning electron microscopy, UV-Vis spectra and photoluminescent spectra were employed to characterize the samarium pyrazine-2,3,5,6-tetracarboxylate samples. The experimental results indicate that the pH value of the solution has an obvious impact on the morghologies and photoluminescent properties of the samples. The morphology can be easily controlled from nano-size to sub-micron particles by changing the pH value. All the samples show three emission peaks at 563, 598 and 644 nm, which are assigned to the characteristic emission transitions 4G5/2→6H5/2, 4G5/2 →6H7/2 and 4G5/2→ 6H9/2 of Sm3+ ions. Moreover, the samples synthesized at the pH value of 7 demonstrate the strongest emisstion compared with other samples.关键词：samarium complex;precipitation method;synthesis;morphology;photoluminescence93|71|2更新时间：2020-08-12
- 摘要：Bismuth (Bi3+) and phosphorus (P3+) ions doped YVO4:Eu3+ down-conversion materials were prepared by modified sol-gel method to broaden the absorption range of ultraviolet light and enhance the stability of light emission. It is shown that some positions of Yttrium (Y3+) and Vanadium (V5+) ions can be successfully replaced by incorporated Bismuth (Bi3+) and phosphorus (P3+) ions in the YVO4 lattice. As to low Bi3+ doping, the crystal structure is still tetragonal and the position of Y3+ is well substituted by Bi3+. While for low P3+ doping, a homogeneous solid solution is formed between YVO4 and YPO4.Under the excitation of 325 nm, the highest luminescence intensity can be obtained with Bi3+ mole fraction of 0.04 and P5+ mole fraction of 0.10, respectively. In that case, the instensity of YV0.90P0.10O4:0.05Eu3+ can increase up to 1.9 times comparing to YVO4:0.05Eu3+.关键词：yttrium vanadate;down-conversion;doping modification105|94|2更新时间：2020-08-12
- 摘要：NaYF4 nanoparticles coated with unsaturated functional groups were co-polymerized with methyl methacrylate (MMA) monomers through covalent bands to synthesize the NaYF4-PMMA luminescent polymer based nanocomposites. The covalent bands between the nanoparticles and the polymer made the upconversion nanoparticles stably embedded in the polymer matrix with high doping concentrations. No obvious aggregations of nanoparticles were observed. The size of NaYF4:20%Yb,2%Er nanoparticls used in the experiment was 9-14 nm, and the size of NaYF4:20%Yb, 1.5%Tm nanoparticls was 11-15 nm. Under the excitation of 980 nm laser, NaYF4:20%Yb,2%Er-PMMA emitted bright yellow light and NaYF4:20%Yb,1.5%Tm-PMMA emitted bright blue light. The emission spectra of the nanocomposites were same with the corresponding nanoparticles. The experiment results showed that these nanocomposites possessed very good transparency in visible region. This kind of upconversion luminescent polymer based nanocomposites had potential applications in the field of display, especially the true three-dimensional (3D) volumetric display technique.关键词：upconversion luminescence;polymer based nanocomposites;rare earth nanocrystals140|45|1更新时间：2020-08-12
- 摘要：The wurtzite AlN microrods were synthesized by direct nitriding metal Al without catalyst using the direct current arc discharge method. The structure, morphology and luminescence property of the as-synthesized samples were characterized by Raman spectra, SEM and PL spectra. The length and diameter of AlN microrods are nearly 30 μm and 10 μm, respectively. There are two emission peaks in the PL spectrum of AlN microrods. The emission at 430 nm can be ascribed to DAP(donor-acceptor pair) radiation transition from deep donor level of VN to deep acceptor (VAl-ON)2-. The emission at 650 nm can be ascribed to the radiation transition between deep VAl acceptor and valence band. When the excitation wavelength changes from 270 nm to 300 nm, the intensity of the emission peak at 430 nm is strengthened and then weakened, and when the excitation wavelength is 285 nm, the intensity is maximum. The intensity of the emission peak at 650 nm increases with the increasing of the excitation wavelength.关键词：AlN microrods;direct nitridation method;photoluminescence;defect luminescence106|163|3更新时间：2020-08-12
- 摘要：A series of luminescent emission-tunable phosphors Ca12Al14O32F2:xEu were synthesized by combustion method. X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM) and photoluminescence spectra (PL) were used to characterize the phosphors. The effects of combustion temperature, ammonium fluoride, urea, boric acid and co-activator Eu3+-Eu2+ on the luminescent properties of the phosphors were also studied. The results show that the emission color of the prepared phosphors can be tuned appropriately from orange red to blue by adjusting the synthesis condition due to the coexistence of Eu3+ and Eu2+.138|60|4更新时间：2020-08-12
- 摘要：In order to reveal the spectral radiant characteristics of the aluminum atoms during hypervelocity impact on 2A12 aluminum target, a two-stage light gas gun loading system and a spectrometer acquisition system were used to collect spectral radiant intensity of three different experimental conditions. The level of Al atom in 2A12 aluminum target was theoretically described combining with quantum mechanics. The results show that the graphical of change between the relative probability 4πr2R2 of discovery electronics and distance r from the center of the atom is fluctuant electronics motion in level and its vicinity in the spherical shell of Al atoms. The probability of the electron in the nucleus is most likely to occur at the level of the energy level, and the probability of the electron around the energy level is small. The atomic spectra of Al are broadened. The probability of the electron's energy level transition or the absorption of energy is also changed with the change of the position of the electrons in the atom. With the increase of the impact velocity, the radiation intensity of spectral lines of the shorter wavelengths increases faster, and the radiation intensity of spectral lines of the longer wavelengths increases slowly.关键词：hypervelocity impact;2A12 aluminum target;energy level transition;quantum mechanics;spectral radiant intensity111|58|2更新时间：2020-08-12
- 摘要：A series of Dy3+ doped B2O3-ZnO-Na2O-Al2O3 glasses (BZNA:xDy) were prepared by high temperature melting method. The structure,composition and luminescence property of BZNA:xDy samples were characterized through FTIR, UV-Vis-NIR and fluorescence spectra. The absorption spectra showed the characteristics peaks of glass substrate and the energy level transition of Dy3+. Under 350 nm excitation, the luminescence intensity, ratio of yellow and blue emission peaks, fluorescence lifetime, color coordinate and color temperature of BZNA:xDy samples can be adjusted and changed according to the content of Dy3+. The luminescent intensity of Dy3+ doped samples are observed to be enhanced firstly and then decrease after 1.0% of Dy3+ mole fraction. Thus, the concentration quenching of Dy occurs in the samples. Meanwhile, the fluorescence lifetime of samples decreases with the increasing doping concentration of rare earth ions. Furthermore, the chromaticity coordinates values and the color temperatures of the emission are reduced gradually.关键词：Dy3+doped;borate glass;luminescent glass;concentration quenching;fluorescent lifetime140|66|1更新时间：2020-08-12
- 摘要：NaYF4:Ce3+,Tb3+/NaYF4:x%Ce3+ core/active-shell was prepared. The complete processes of excitation, energy migration, from photon absorption to emission were dissected to unravel the role of sensitizers doped in shell in every individual stage. The experiment results reveal that the essence of doping sensitizers in the shell is just to increase the absorption efficiency whereas the quantum yield is lessened simultaneously. The optimal sensitizer doping concentration is also fixed to achieve the best luminescence performance. In order to obtain the best enhanced luminescence effect, the doping concentration of the sensitized ions in the shell must be lower than that of the bare core.关键词：rare earth doped;active shell;nanomaterial;luminescent efficiency94|50|0更新时间：2020-08-12
- 摘要：The nondoped emitting layer (EML) was constructed by introducing a ultrathin layer of pure green phosphorescent dye tris(2-phenylpyridine)iridium between a hole transporting layer TCTA and an electron transporting layer TPBi. The device structure is ITO/MoO3(2 nm)/NPB(40 nm)/TCTA(10 nm)/Ir(ppy)3(0.1-0.5 nm)/TPBi(40 nm)/LiF(1 nm)/Al(80 nm). The thickness of EML can affect the performance of green phosphorescent organic light emitting diodes (PhOLEDs). By changing the thickness of emitting layers, the best performance of green PhOLEDs can be achieved with a 0.2 nm pure phosphorescent dye. The device exhibits highly efficient green emission with a maximum luminance of 26 350 cd·m-2, a maximum current efficiency of 42.9 cd·A-1 and a maximum external quantum efficiency of 12.9%. These results indicate that the high performance PhOLEDs can be realized with only ultrathin nondoped EMLs in a simple way.关键词：ultrathin nondoped emissive layer;organic light-emitting diodes;excitons107|236|2更新时间：2020-08-12
- 摘要：Nanorod structure is an effective method to release the strain in multiple quantum wells of InGaN/GaN green LED with high In component. In this paper, the natural lithography with self-assembled polystyrene microspheres, inductively coupled plasma dry etching and wet-etching using KOH aqueous solution were used to fabricate the nanorod structure with three heights in GaN-based green LED epitaxial wafers. The morphology was observed by scanning electron microscope, and the photoluminescence (PL) spectra at room temperature and 10 K low temperature were characterized. It is shown that the strain relaxation significantly affect the piezoelectric field, thereby the nanorod structure leads to a promotion of the wafers' internal quantum efficiency (IQE) and blue-shift of the peak wavelengths of PL spectra, and the nonuniform distribution of the strain causes a broadening of the FWHM (full width at half maximum). Compared with the ordinary planar structure, the nanorod structure with the height of 747 nm induces an enhancement of 917% for the IQE, a blue-shift of 18 nm for the peak wavelengths of PL spectrum, and a broadening of 7 nm for the FWHM. The results also indicate that the decreasing of effective active area of samples with nanorod structure may reduce the FWHM.关键词：GaN-based LED;green LED;nanorod structure;photoluminescence spectrum94|342|4更新时间：2020-08-12
- 摘要：The temperature dependence of amplified spontaneous emission (ASE) from blend film of poly(9,9-dioctylfluorene-co-benzothiadiazole) (F8BT) and poly(3-hexylthiophene) (P3HT) was investigated. ASE from blend film with various P3HT mass ratio and F8BT film in the range of 80-320 K was measured. The results show that the threshold of blend film decreases at first and then increases at room temperature with the increasing of P3HT ratio. Low ASE threshold about 2.59×103 W/cm2 is achieved for the blend with 20% P3HT ratio. When the temperature dropped from 320 K to 80 K, ASE threshold of the blend with 20% P3HT decreases from 2.84×103 W/cm2 at 320 K to 2.03×103 W/cm2 at 80 K, and ASE output intensity at the pump intensity of 5.29×103 W/cm2 increases fourfold. Meanwhile, a 12 nm redshift in ASE wavelength of the blend film is found with the reducing of the temperature.关键词：amplified spontaneous emission;temperature dependence;blend polymer waveguides;threshold87|114|1更新时间：2020-08-12
- 摘要：Vertical structured thin film GaN LEDs on Si substrate were fabricated by wafer boding and substrate removing process. The LED chips were annealed at various temperatures, and high-resolution X-ray diffraction (HRXRD) measurements were performed to analyze the stress in GaN films. The results show that the annealing within 160-180℃ can obviously reduce the stress in GaN thin film, and the stress can be fully released at 200℃ and the measured lattice constants are close to the standard values of bulk GaN. Annealing at higher temperatures, the lattice constants of the GaN films only slightly fluctuate around the standard values. Scanning electron microscope (SEM) was used to analyze the cross-sectional morphology of the bonding layers. The evolution of the stress in GaN film can be well explained by the alloying degree of the Ag-In layers.关键词：Si substrate;GaN;stress;XRD;Ag-In117|117|2更新时间：2020-08-12
- 摘要：Single layer WS2 was synthesized by atmospheric pressure CVD method. The mono-WS2 of triangular grain was grown by the single controlled quartz tube furnaces on well cleaned sapphire substrates. The grain size could be controlled by adjusting the experimental conditions. Optical microscopy, Raman spectroscopy, and photoluminescence emission spectroscopy were utilized to characterize WS2 samples. The Optical microscopy shows the length of triangle domain up to 120 μm and the uniform of WS2. Raman spectrum of a WS2 single domain demonstrates the characteristic E12g (in-plane vibrational) mode and A1g (out-of-plane vibrational) mode at 355.1 cm-1 and 418.1 cm-1, respectively. The frequency difference between E12g mode and A1g mode is 64 cm-1 which matches the single-layer-thick WS2 films. The PL peak of WS2 is located at 619 nm (2.0 eV) which consistents with its direct-band-gap. Furthermore, the PL intensity of monolayer WS2 is very strong, which reveals its high crystalline. The experiment results demonstrate that the large size mono-WS2 flakes with high crystalline can be synthesized controllable on sapphire. The effects of some essential growth parameters such as the temperature, the growth time and the precursor on the controlled growth of mono-layer WS2 are also discussed.关键词：monolayer WS2;chemical vapor deposition;Raman spectroscopy;photoluminescence spectroscopy151|67|3更新时间：2020-08-12
- 摘要：Tapered diode laser with ridge waveguide was introduced and formed through etching the wafer with asymmetrical waveguide structure and double quantum walls. In the laser, the negative effect of p-cladding layer was decreased and the vertical divergence angle was reduced. The high brightness power is arrived on account of the combination of the ridge waveguide and the taper waveguide. In experiment, the laser delivers 976 nm and 4 W CW at 7 A current. The slow direction beam quality and the fast direction beam quality are measured of 1.593 mm·mrad and 0.668 mm·mrad, respectively.关键词：diode laser;tapered waveguide;ridge waveguide;high brightness;high beam quality182|214|6更新时间：2020-08-12
- 摘要：In order to present the process of mode competition with increasing injected current in the proton-implanted vertical cavity surface emitting laser (VCSEL), the electric field, carrier, optical and temperature in its lasing were studied in the three dimensions. The opto-electro-thermal self-consistent simulation for the proton-implanted VCSEL under CW operation at room temperature was given after the equations for electric field, carrier, optical and temperature were shown. The voltage electrode and output power were obtained in the proton-implanted VCSEL with current aperture radius r=4 μm and threshold injected current Ith=4.5 mA under the injected current Iin=5.0, 5.5, 6.0 mA, respectively. The distributions of electric field, carrier, optical and temperature were obtained in the continuous wave proton-implanted VCSEL. The dependent of the output power on the injected current in proton-implanted VCSEL was also derived. The results show that the injected current density is improved and expanded respectively with the increasing of the injected current. The first order transverse mode increases higher than the transverse fundamental mode while the two laser transverse modes are both improved. The output energy is gradual transition to the first order transverse mode. The space burn for carrier in the activity region is found as the mode competition. The laser transverse mode in continuous wave operation for proton-implanted VCSEL with current confinement radius r ≥ 4 μm is unstable.关键词：vertical-cavity surface emitting laser (VCSEL);transverse modes;opto-electro-thermal simulation126|133|0更新时间：2020-08-12
- 摘要：The failure mechanism of white LED negative electrode shedding phenomenon was investigated. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were used as two main techniques to characterize the surface morphology and composition of the chip. SEM shows that the surface of negative electrode dropped off is coarse, and granular crystals are formed in the transparent conductive film. Chlorine element has been detected in both corroded negative electrode part and the packaging glue by EDS testing. It is found that the electrochemical corrosion between chloridion and aluminum is the main reason to result in LED failure.关键词：LED;failure analysis;electrode;corrosion88|168|3更新时间：2020-08-12
- 摘要：In order to overcome the non-uniformity defects of image vignetting captured by camera in dot-to-dot correction on LED display screen, a vignetting correction method based on LED display screen and discrete position luminance measurement was put forward. First, the process of camera image acquisition and imaging features of LED display were analyzed. From this, a correction method of camera vignetting was proposed, a fitting surface of camera vignetting was obtained. Then, a vignetting correction factor matrix corresponding pixels on camera sensor was calculated. Using the above method, an experiment of single-box luminance correction of LED display screen was conducted. Experimental results indicate that the uniformity deviation of LED display screen can be narrowed from 6.69% to 1.49% after image vignetting factor calibration. After correction of camera image vignetting, non-uniformity surface distribution can be completely eliminated. Therefore, the "center-dark, surround-bright" defect on LED display screen is overcome, and the desired correction effect for multi-screens stitching display is achieved.关键词：LED display screen;vignetting calibration;image uniformity;surface fitting98|167|2更新时间：2020-08-12
- 摘要：The hyper-spectral imaging technology was applied to build a prediction model for soluble solid content of Lingwu jujube at different preservative temperature. The average spectra data were extracted from the area-of-interest of the image. After pre-treatment of different spectrum, the succession projection analysis (SPA) was used to select characteristic wavelength. 13 characteristic wavebands under 4℃ temperature condition (421, 426, 512, 598, 641, 670, 675, 723, 814, 906, 944, 978, 982 nm) and 12 characteristic wavebands under normal temperature condition (425, 507, 555, 598, 673, 680, 685, 718, 809, 910, 954, 978 nm) were extracted. By adoption of MSC treatment, MSC+SPA treatment, Savitzky-Golay smooth treatment and SNV treatment, both MSC treatment and MSC+SPA treatment out of 4 above were screened out as the optimum pre-treatment method afterwards. In corresponding to these 2 optimum pre-treatment methods, 3 prediction models like partial least squares regressions (PLSR), support vector machine (SVM) and principal component regression (PCR) model were built, respectively. Among the aforesaid 6 prediction models, 2 optimum modes such as PLSR model after treated by MSC (RC2:0.852, RMSEC:0.940; RP2:0.857, RMSEP:0.894) and PLSR model after treated by MSC+SPA (RC2:0.872, RMSEC:0.866; RP2:0.787,RMSEP:1.007) were acquired. The results show that the content of soluble solids of Lingwu jujube at different preservative temperature can be forecasted by utilization of hyper-spectral imaging technology in combination of building multiple prediction models, so that the nondestructive testing (NDT) can be achieved for Lingwu jujube in accurate and rapid manner.关键词：hyper-spectral imaging;soluble solid;successive projections algorithm;partial least squares138|614|6更新时间：2020-08-12
- 摘要：Three-dimensional fluorescence spectroscopy and two-dimensional fluorescence correlation spectroscopy were applied for identification of two kinds of pyrethriod pesticide in tea liquor. Based on the local minima of image algorithm, the location of peaks in three-dimensional fluorescence spectrum or two-dimensional fluorescence correlation spectrum was obtained, which made the identifucation of the two pesticide in tea liquor be realized by peak point matching. The results show that it is not suitable to identify the pesticides through three-dimensional fluorescence spectrum for the peaks' overlap. However, two-dimensional fluorescence correlation spectroscopy can overcome the shortcoming and identify the pesticide in its mixture no matter how much the concentration of the pesticide is. In the actual tea liquor, identification rate of fenvalerate is 80% and identification rate of alphacypermethrin is 83%, which illustrates 2D fluorescence correlation spectroscopy is an effective identification of the two pyrethriod pesticide (fenvalerate, alphacypermethrin) in their mixture.关键词：three-dimensional fluorescence spectroscopy;two-dimensional fluorescence correlation spectroscopy;local minima;pyrethriod pesticide;identification125|98|4更新时间：2020-08-12
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