最新刊期
卷 38 ， 期 3 ， 2017
- 摘要：Eu-doped 5Li2O-1Nb2O5-5TiO2 (LNT) luminescent dielectric ceramics were synthesized by solid state reaction method with Li2CO3, Nb2O5, TiO2 and Eu2O3 as raw materials. The properties of LNT:0.2%Eu3+(mass fraction)ceramics were characterized by density test, X-ray diffraction(XRD) and photoluminescence spectroscopy, respectively. The XRD results show that the ceramics sintered at 1 120℃ consist of ‘M-phase’ and Li2TiO3 solid solution, no other miscellaneous phase. Under 400 nm excitation, strong red-orange luminescence can be observed. The red emission at 615 nm belonging to 5D0→7F2 transition is an electric dipole transition, while the orange emission at 592 nm corresponding to 5D0→7F1 transition is a typical magnetic dipole allowed transition.关键词：solid state reaction method;Eu-doped;emission spectrum;excitation spectrum141|56|2更新时间：2020-08-12
- 摘要：Novel hybrid nanoparticles Ag@Fe3O4@C-CdTe@SiO2 were prepared. The synthesis method is included of a Fe3O4 magnetic embedded Ag core (Ag@Fe3O4), an interlayer of carbon modified by PEI to form sufficient amounts of amine functional groups (Ag@Fe3O4@C-PEI), the grafting of CdTe quantum dots (QDs) on the surface of Ag@Fe3O4@C-PEI (Ag@Fe3O4@C-CdTe), and an ordered SiO2 structured shell. The nanocomposites possess an average diameter of 150 nm, orange emission feature and the saturation magnetization of 224 A/g (22.4 emu/g), which has room temperature ferro-magnetism. The photoluminescence measurement reveals that the fluorescence of Ag@Fe3O4@C-CdTe nanostructures in this composite with the Ag cores of about 45 nm has more enhancement compared with that of Fe3O4@C-CdTe nanostructures due to the strong surface plasmonic resonance of the Ag cores.关键词：multifunctional nanoparticles;noble metal;enhanced-luminescent;core-shell116|41|0更新时间：2020-08-12
- 摘要：Upconversion NaErF4:Yb,Gd nanocrystals with bright red emissions were prepared via a facile solvothermal method. The crystalline phase, size and the relative intensity of upconversion luminescence can be simultaneously manipulated by adjusting Gd3+ ions contents. The introduction of Gd3+ can effectively promote the cubic to hexagonal phase transformation, size reduction and obviously upconversion luminescence (UCL) intensity improvement of NaErF4:Yb,Gd nanocrystals. XRD, TEM and UCL spectra results reveal that the sample co-doped with 25% Gd3+ ions (mole fraction) of NaErF4:Yb system exhibits the optimized structural and optical properties. Meanwhile, the mechanism involving upconverting photon excitation and energy transfer between Yb3+ ions and Er3+ ions were investigated under the excitation of 980 nm diode laser.关键词：NaErF4;Gd3+ doping;upconversion luminescence232|56|0更新时间：2020-08-12
- 摘要：The fluorescent nanoprobe for the detection of DNA was established by utilizing mercaptopropionic acid coated InP@ZnS QDs and Dured. In this nanoprobe. The InP@ZnS QDs/Dured fluorescent nanoprobes were structured by electrostatic interactions between environment friendly, negatively charged InP@ZnS quantum dots and positively charged Dured, and then the fluorescence of InP@ZnS QDs/Dured was quenched through fluorescence resonance energy transfer (FRET). At presence of DNA, DNA and Dured were specific binding, which enable Dured removing from the surface of InP@ZnS QDs and achieving fluorescence recovery of InP@ZnS QDs. Thus, the detection of DNA was realized. The linear range of the InP@ZnS QDs/Dured fluorescent nanoprobes for DNA detection and the detection limit were 2.0-275.0 ng·L-1 and 1.0 ng·L-1, respectively. The InP@ZnS QDs/Dured fluorescent nanoprobes can be also used in rapid detection of DNA under simulated physiological conditions.关键词：InP@ZnS quantum dots;fluorescent probe;DNA;FRET214|42|2更新时间：2020-08-12
- 摘要：A series of self-activated vanadate phosphors Na2Y1-xMg2 (VO4)3:xEu3+ (x=0.15-0.75) were prepared by sol-gel method. The phase formation, surface morphology and luminescence properties of the samples were verified by XRD, SEM, photoluminescence spectra and decay curves. It is found that the obtained samples are pure crystalline phases with garnet structure. The particles with a diameter ranging from 0.3 to 1 μm show irregular shapes and have a tendency to be agglomerating. This host can be excited by ultraviolet (UV) light, and it exhibits a broad-band green emission in the region from 400 to 700 nm, ascribing to the charge transfer of VO43- groups. Na2YMg2 (VO4)3:Eu3+ phosphors show both characteristic broad-band emission from VO43- groups and sharp emissions from Eu3+ ions upon 340 nm UV light. Moreover, the intensities of host and Eu3+ emission depend on the doping concentration of Eu3+. The energy transfer from VO43-to Eu3+ was discussed based on spectrum analysis and decay curves.关键词：self-activated;Na2YMg2 (VO4)3:Eu3+;energy transfer;fluorescence lifetime124|48|4更新时间：2020-08-12
- 摘要：Organic nanomaterial PTTC was prepared by directly self-assembling in the gas phase with a thermal vacuum evaporation process. The product was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), infrared spectrum(IR)、fluorescence spectrum and differential thermal analysis(DTA). The PTTC nanomaterial can be solubilized in the solution of Tween 20, and L-lysine has strong sensitizing effect for the fluorescence of the dispersion system. A nano-fluorescent chemical sensor of L-lysine is built based on the above results. The linear range is 7.00×10-4-5.40×10-7 mol/L with the detection limit of 8.39×10-8 mol/L. Further study show that the current difference of cyclic voltammogram of L-lysine is reduced by PTTC nanostructure, and it is expected to prepare a nano electrochemical sensor of L-lysine in the future.关键词：3;4;9;10-perylenetetracarboxylic(PTTC);thermal vacuum evaporation and molecule self-assembly method;organic nanomaterials;L-lysine;chemical sensor122|73|1更新时间：2020-08-12
- 摘要：The effect of γ-ray irradiation on the performance parameters of commercial off the shelf CMOS active pixel sensors was studied, specially focusing on the analysis of quantum efficiency, conversion gain, dark current, dead pixels, and pulse parameters such as particle noise pixels. As result shown, the active pixel sensors incapacitated after 1 000 Gy γ-ray irradiation present as no signal output or pixel gray value of only 0, 110 or 255 DN. The displacement cross section of cobalt-60 of γ-ray is about 10-25 cm2(0.1 b). After short time and low dose rate irradiation below 58.3 Gy/h, the irradiation has less effect on the quantum efficiency and conversion gain, the number of dead pixels is still zero, and the background noise of 3T APS rise up to 4.62 DN but less effect on 4T-APS. The frequency of the gray value of the dark image caused by the pulse noise is in Poisson distribution and correlated with γ-ray radiation dose rate.关键词：active pixel sensor;γ-ray;total ionizing dose effect;ionizing radiation effect143|35|4更新时间：2020-08-12
- 摘要：Surface-enhanced Raman spectroscopy(SERS) is a high sensitive detecting technology, which is very promising in chemical and biological analyzing applications. Noble metals which own the unique characteristic of localized surface plasmon resonance and the substrates are two important factors. In this paper, we used PS (polystyrene) spheres as templates to fabricate three-dimensionally ordered TiO2 nanostructure (TiO2-3DOM) and investigated the influence of the way to combine Ag nanoparticles with TiO2-3DOM on its SERS performance. The results tell that TiO2-3DOM/Ag obtained through silver mirror reaction is a very sensitive substrate, its detecting limitation to Rhodamine 6G (R6G) can reach 10-10 mol/L.关键词：TiO2;three-dimensionally ordered porous TiO2 nanostructure;Ag;surface-enhanced Raman spectroscopy(SERS)125|57|0更新时间：2020-08-12
- 摘要：The morphology of Ag nanoparticles influences the photoluminescence (PL) efficiency of InGaN/GaN multiple quantum wells (MQWs) dramatically. In this paper, the ion beam deposition (IBD) technique was employed to deposit Ag on the surface of InGaN/GaN MQWs, and then Ag nanoparticles were fabricated by thermal annealing process. Ag nanoparticles with different morphology were obtained by adjusting the deposition time. For each sample, the morphology of Ag nanoparticles was characterized by AFM. In addition, the absorbance spectra, room and variable temperature PL spectra and time resolved PL (TRPL) spectra were carried out to determine the optical properties of the samples. The results show that the diameters of Ag nanoparticles increase with the increasing of deposition time, and the aspect ratio increases first and then decreases. Moreover, a red shift of the absorption peak of Ag nanoparticles is observed. Compared with the sample without Ag nanoparticles, the room temperature PL integrated intensity of the sample with Ag deposition time of 15 s is suppressed 6.74 times. For the samples with Ag deposition time of 25 s and 35 s, the PL integrated intensities are enhanced 1.55 and 1.72 times, respectively. Meanwhile, a red shift occurs in the peak position. Whereas, there is no obvious change in PL integrated intensity for the sample with Ag deposition time of 45 s. This phenomenon can be attributed to the difference morphology of Ag nanoparticles on each sample. The morphology of Ag nanoparticles influences the coupling strength between the localized surface plasmons (LSPs) in Ag nanopaticles and the excitons in MQWs. The light scatting ability of Ag nanoparticles is also influenced by its morphology. The measurement results of TRPL and variable temperature PL demonstrate that the change of room temperature PL integrated intensity is induced by the coupling between LSPs and the excitons in MQWs. Finally, it is found that Ag nanoparticles with bigger aspect ratio and absorption spectrum overlap PL spectrum of MQWs more can better enhance the PL intensity of InGaN/GaN MQWs.关键词：ion beam deposition;Ag nanoparticles;localized surface plasmons;InGaN/GaN MQWs;photoluminescence124|66|1更新时间：2020-08-12
- 摘要：852 nm semiconductor laser was manufactured by metal organic chemical vapor deposition (MOCVD) and semiconductor subsequent technology. The threshold current of this laser was 57.5 mA, output spectral line width was less than 1 nm at room temperature. The impact of temperature on output optical power, threshold current, voltage, output centre wavelength was analyzed. When the temperature changes from 293 to 328 K, the characteristic temperature is 142.25 K, and the rates of the threshold current change and output light power are 0.447 mA/K and 0.63 mW/K, respectively. Ideal factor n is calculated to be 2.11, while the laser thermal resistance is calculated to be 77.7 K/W. The calculated center wavelength drift rate is 0.249 29 nm/K, corresponding well to the measured value in the experiment. Experimental results demonstrate that the relevant parameters of this laser are stable with the temperature ranging from 293 to 303 K. However, a temperature device is needed if a higher working temperature is required.关键词：852 nm semiconductor laser;temperature characteristic;threshold current;characteristics of the temperature116|87|2更新时间：2020-08-12
- 摘要：Light extraction efficiency (LEE) of flip-chip thin-film LEDs (FC-TFLEDs) with different surface textures were performed by using finite difference time domain method. The surface textures and different thicknesses of p-GaN layer were optimized for high LEE FC-TFLEDs. It is found that the maximum LEE of FC-TFLEDs with photonic crystals and hexagonal cones is 1.56 and 1.97 times to that of FC-TFLEDs with flat surface, respectively. Both types of the surface textures can improve the LEE of FC-TFLEDs, however, it is much difficult to obtain high LEE FC-TFLEDs by employing photonic crystals. The simulated results show that the LEE of FC-TFLEDs is effectively improved by the use of the hexagonal cones, in addition, it can greatly reduce the difficulty in LED material growth and device fabrication.关键词：FC-TFLED;FDTD;light extraction efficiency;photonic crystals;hexagonal cone122|83|1更新时间：2020-08-12
- 摘要：The electrical and optical properties of GaN-based high power LEDs were investigated under both DC and AC bias. The results show that the carrier distribution of the active region can be modified by changing the indium concentration of the last quantum barrier. The accumulated electrons in the active region can lead to the negative capacitance effect. The improved carrier transport property for LEDs with lower quantum barrier also helps to increase the recombination rate and modulation bandwidth by 20%. This work will help to understand the influence of carrier distribution on the frequency behavior of GaN-based LEDs.关键词：GaN-based;light emitting diodes;visible light communication;modulation bandwidth;carrier distribution133|80|0更新时间：2020-08-12
- 摘要：An optical waveguide amplifier at 655 nm based on KMnF3:Yb3+,Er3+ nanocrtstals-PMMA covalent-linking nanocomposites pumped by a 980 nm laser diode was demonstrated. The absorption spectrum indicates that the nanocrystals have significant absorption at 980 nm. The fluorescence spectrum was measured under the excitation of 980 nm laser. An optical waveguide amplifier with embedded structure was fabricated using KMnF3:Yb3+,Er3+ NCs-PMMA nanoparticles as the core layer. A relative gain of 2.7 dB at 655 nm wavelength was obtained when the input signal power was 0.1 mW and pump power was 260 mW in a 1.1 cm-long waveguide.关键词：nanocrtstals;polymer;optical waveguide amplifier;upconversion emission125|50|0更新时间：2020-08-12
- 摘要：To improve the performance of organic solar cells (OSCs) and enhance their stability in the air, the effect of TiO2 film as cathode buffer layer on the performance of OSCs was studied. The cells with a structure of ITO/TiO2/C70/Rubrene/MoO3/Al were fabricated. The influence of TiO2 on the cell was investigated by measuring the device efficiency. The experimental results show that the performance of cell is on the rise with the increase of the thickness of TiO2. when the thickness of TiO2 is 81 nm, the performance parameters are the best (power conversion efficiency current density, open circuit voltage and fill factor are 1.09%, 2.55 mA·cm-2, 0.88 V, 48.69%, respectively), and the cell performance declines with the continued increasing of TiO2 thickness. Compared with the device without TiO2 layer, the optimal Jsc, Voc, FF and PCE of the cells increased by 37%, 21%, 17% and 91%, respectively. and the reasons for the improvement were discussed.关键词：organic solar cells(OSCs);TiO2;cathode buffer layer;Rubrene;C70120|48|3更新时间：2020-08-12
- 摘要：In order to improve the cooling capacity of LED lamps and lanterns, a new type of LED lamp radiating structure was designed based on the principle of the chimney effect. The new type of LED lamp without radiator only used a cylindrical substrate break through the traditional mode of construction of LED lamps. A three-dimensional model was built by adopting Solidworks, and its plug called Flow Simulation was used to simulate the model. The highest temperature of LED chip is 81.34℃ when the power is 10 W. The highest temperature changes to 105.54℃ at 15 W, higher than the security temperature of LED chip. Therefore, an improved scheme of joining the radiator in the middle of the substrate was put forward. Then, the maximum temperature of LED chip reduces by 30.79℃. Based on the model in which the number of fins is 12, the diameter of inner ring is 20 mm, the thickness of fins is 1 mm, the thermal simulation was carried on. The results show that the special-shaped LED lamp has the best cooling capacity when the number of fins is 12, the diameter of inner ring is 12 mm, and the thickness of the fins is 1 mm. At the moment, the highest temperature is 72.21℃. The temperature of LED lamp can all meet the security requirements when the power of the special-shaped LED lamp is 8, 13, 15, 17 and 19 W. The experiment results of 8 W LED lamp show that the highest temperature is 53℃, higher than the results of the simulation results only 1.01℃. It confirms the correctness of the simulation. In conclusion, the designed special-shaped LED lamps provide a new way to solve the heat dissipation problem of high power LED.关键词：cylindrical;special-shaped LED lamp;chimney effect;highest temperature;radiating;without radiator159|93|4更新时间：2020-08-12
- 摘要：In order to study mechanism of activation and conversion of coalbed methane under cold plasma, the investigation was realized by dielectric barrier discharge of gas mixture of CH4, O2 and N2 (the volume fraction of CH4, O2 and N2 is 40%, 12% and 48%, respectively). In this study, a set of experimental system of plasma activation and conversion of coalbed methane was constructed. The experiment system was used to study affecting factors of activation and conversion of coalbed methane, such as discharge voltage and discharge frequency. Based on this, the stable products of coalbed methane conversion were analyzed by the gas chromatograph, As main stable products of conversion of coalbed methane under cold plasma, CH3OH, CO and CO2 were detected. In situ diagnosis technique of optical emission spectroscopy was used to study the emission spectra of the gas discharge in the spectra range of 200-700 nm, active species of O·, CH·, C·, Hα and N2(A3∑U+) were observed. Based on the detection of the active species, the analysis of stable products by gas chromatograph and the characterization of plasma, the course of free radical reaction of the activation and conversion of coalbed methane under cold plasma were inferred. Meanwhile, it is clarified that N2 in the mixture gas has promoting effect on activation of coalbed methane and production of main products. That is, N2 produces metastable ions with longer survival time. The metastable ions transfer the energy to O2 and CH4 in the mixture gas, which accelerates the activation of methane and formation of main stable products.关键词：optical emission spectroscopy;coalbed methane;cold plasma;mechanism123|69|6更新时间：2020-08-12
- 摘要：The electron population oscillating between the ground and metastable level in the beat frequency between the pump and probe beam can result in the reduced absorption of the probe wave. The probe wave experiences the reduction of absorption in a narrow frequency band, which corresponds to rapid changes of the refractive index. According to the equation of ng=n(ω)+ωdn/dω, the group refractive index will increase. Utilizing the theory of slow light, the limitation of group refractive index in different environments and the change of group velocity were discussed. It is found that the group refractive index decreases with the increasing of the fiber length. The group refractive indices in the fibers with different Er3+ concentration decrease with the increasing of the modulation frequency, and the group refractive index has a saturation process with the increasing of the signal power under different modulation frequency.关键词：optical fiber;group refractive index;slow light122|80|0更新时间：2020-08-12
- 摘要：Two complexes of rare earth with sorbic acid (SA) and 8-hydroxyquinoline (Hq) were synthesized and the interaction with DNA were investigated. The rare earth complexes were characterized by elemental analysis, IR, UV-Vis, TG-DTA and molar conductance. The compositions of the complexes were confirmed to be Sm(Hq)(SA)2 and Eu(Hq)(SA)2. The interactions between complexes and herring sperm DNA were investigated by spectral methods. The absorption peaks of the complexes shift and are weakened with the interaction of DNA. Moreover, accompanied by a red shift, the absorption peak intensity of complex-DNA system is weakened with the adding of NR. The absorption peak intensity and position of NR-DNA system change with the adding of complex, indicating a new balance system among complex, NR and DNA. The combining ratios of Sm(Ⅲ) complex and Eu(Ⅲ) complex with DNA are all 5:1, the binding constants are 2.04×104 and 1.09×104 L/mol at 20℃, respectively. The complex can remarkably quench the emission intensity of NR-DNA system. All the above results indicate that the interaction mode of the complexes with DNA belong to intercalative, and the sequence of binding ability of the complexes to DNA is Sm(Hq)-(SA)2>Eu(Hq)(SA)2.关键词：sorbic acid;8-hydroxyquinoline;rare earth;herring sperm DNA;interaction134|81|1更新时间：2020-08-12
- 摘要：The 3×3 coupler-based Michelson interference demodulation system was established to achieve a stable demodulation of distributed feedback optical fiber laser sensor (DFB FL) in a wide dynamic range. The symmetric demodulation algorithm (NPS) and arctangent demodulation algorithm used in this system were in-depth researched. Firstly, the theory of the 3×3 coupler-based demodulation algorithm and calibration method used in asymmetry coupler were presented. Secondly, the selection of minimum unbalanced interferometer path length, as well as the relation of system noise and frequency noise of laser were analyzed. Next, the amplitude of the maximum demodulated signal of NPS and the arctangent algorithm were compared. At last, the effect of differentiator on the dynamic range of NPS method was analyzed. The experiment results show that the dynamic range of NPS method is wider than that of arctangent algorithm, and a bad amplitude-frequency characteristic of differentiator will narrow the dynamic range of demodulation. The dynamic range of NPS algorithm and arctangent algorithm reaches to 96 dB and 91 dB respectively when the sampling frequency is 125 kHz, signal frequency is 1 kHz, and interferometer's unbalanced length is 100 m. By applying calibration before demodulation, the 3×3 coupler-based demodulation methods may produce a large dynamic range, which can achieve a stable demodulation and meet the requirements of engineering application.关键词：distributed feedback optical fiber laser(DFB FL) sensor;3×3 coupler;passive homodyne demodulation132|51|7更新时间：2020-08-12
- 摘要：Two novel cinnamic acid oxime ester derivatives were designed and synthesized with o-methoxy cinnamic acid and p-substituted benzaldehyde. Their structures were characterized by mass spectrometry, infrared spectroscopy, and nuclear magnetic resonance. The interaction mechanism of derivatives and human serum albumin (HSA) were explored by molecular docking, fluorescence spectroscopy, UV-visible absorption spectroscopy and site marker competitive experiments.The binding constants and corresponding thermodynamic parameters of the derivative-HSA systems were calculated by Stern-Volmer equation. Combined with UV-Vis absorption spectra, the results indicate that the derivatives can get complexes with HSA respectively and strongly quench the intrinsic fluorescence of HSA, and hydrogen bonds and van der Waals forces are main acting forces. Site marker competitive experiments indicate that the binding of the derivatives to HSA primarily take place in sub-domain ⅡA. The above results verify the prediction of molecular simulation experiment.关键词：cinnamic acid ester oxime;spectrometry methodology;site marker competitive;human serum albumin (HSA);molecular docking125|67|1更新时间：2020-08-12
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