最新刊期
卷 39 ， 期 11 ， 2018
- 摘要：Infrared persistent luminescence technology has promising applications in variety of important fields such as deep-tissue biomedical imaging and night-vision security surveillance. This paper presents a brief review on several key aspects, involving the definition of infrared persistent luminescence for reference, the design and choice of emitting ions, the basic knowledge on luminescence dynamic process, and the excitation spectroscopy for infrared persistent luminescence.关键词：infrared persistent luminescence;Cr3+-activated;Yb3+-activated;photo-stimulated persistent luminescence;up-converted persistent luminescence259|303|2更新时间：2020-08-12
- 摘要：Near-infrared persistent luminescent materials are catching extensive attention for their distinctive features in bio-imaging application. However, comparison with the excellent afterglow properties of green and blue persistent luminescent materials, the afterglow of near-infrared persistent luminescent material is urgent to be improved. This paper proposed a persistent energy transfer enhancement strategy to improve the near-infrared afterglow of LiGa5O8:Cr3+ through the radiative energy transfer from SrAl2O4:Eu2+,Dy3+ to LiGa5O8:Cr3+. In this work, SrAl2O4:Eu2+,Dy3+ and LiGa5O8:Cr3+ were synthesized by solid state reaction, and then the afterglow properties were characterized for the composites with various weight ratios. The results show that the near-infrared (718 nm) afterglow decay time of the SrAl2O4:Eu2+,Dy3+/LiGa5O8:Cr3+ composites became longer than pure LiGa5O8:Cr3+, under the excitation of 348 nm. Moreover, the afterglow enhancement was different for various weight ratios composites. When the ratio was 1:1, the afterglow at 718 nm of LiGa5O8:Cr3+ was strongest, indicating the most efficiency of energy transfer. In addition, the TL peaks belonging to SrAl2O4:Eu2+,Dy3+ were recorded in the TL curve, by monitoring at 718 nm. This is a substantial proof for the persistent energy transfer from SrAl2O4:Eu2+,Dy3+ to LiGa5O8:Cr3+. These results demonstrate the feasibility of the persistent energy transfer between two long afterglow luminescent materials, and provide a potential approach to improve the afterglow properties of near-infrared persistent luminescent materials.关键词：persistent luminescent materials;persistent energy transfer;SrAl2O4:Eu2+;Dy3+;LiGa5O8:Cr3+176|59|2更新时间：2020-08-12
- 摘要：The in-situ reduction method was successfully used to prepare the uniform and ultrathin gold shell-coated NSA nanostructures. The microstructure and composition characterizations such as XRD, TEM, EDX, HRTEM-HAADF, mapping as well as absorption spectra data indicated that the average thicknesses of SiO2 shell and gold nanoshell are about 5 nm and 2 nm, respectively. Under the excitation of a CW diode laser of 980 nm, the dependence of the upconversion fluorescence intensity of the core-shell structure on the concentration of chloroauric acid was systematically investigated. The steady-state spectral results show that the red and green upconversion luminescence intensities of NS samples are 2.8 times enhanced simultaneously by coating the gold shell. The upconversion lifetime of the red and green emission levels before and after the gold shell cladding is obtained by fitting the fluorescence decay curves. The mechanism of enhanced upconversion fluorescence by the surface plasmons is discussed based on the spectral analysis and FDTD method simulation.关键词：upconversion luminescence;gold nanoshell;localized surface plasmon;resonance energy transfer;surface enhanced fluorescence154|76|3更新时间：2020-08-12
- 摘要：Considering the thickness of the quantum dot, the eigenvalues and eigenfunctions of the polaron ground state and first exited state in a quantum dot were derived by using the Pekar variational method with the harmonic and Gauss potentials as the transverse and longitudinal confinement potentials, respectively. Based on above two states, a two-level system was constructed. Then, the polaron quantum transition affected by an electric field was discussed in terms of the two-level system theory. The results indicate that the Gauss potential reflects the real confining potential more accurately than the parabolic potential; the influence of the thickness of the quantum dot on the transition probability Q of the polaron is interesting and significant, and must not be ignore; the ground and the first excited states' energies and the corresponding transition probability of the polaron are influenced significantly by some physical quantities, such as the strength α of the electron-phonon coupling, strength F of the electric field, barrier V0 and confinement range L of the asymmetric Gauss potential, suggesting the transport and optical properties of the quantum dot can be manipulated further though those physical quantities.关键词：polaron;thickness effect;asymmetric Gaussian potential;electric field;quantum transition128|194|0更新时间：2020-08-12
- 摘要：Ho3+ doped aluminum germanate glasses adapting for K+-Na+ ion-exchanged waveguide were fabricated by high temperature melting technique. The thermal ion-exchanged waveguide refractive index profile and infrared spectral characteristic of the glasses were measured. These experimental results reveal that the maximum change of refractive index in waveguide glasses is 0.006 9 when Ho3+ doped aluminum germanate glasses are immersed in KNO3 molten salt at 390℃ for 4 h. Effective diffusion depth and coefficient of K+-Na+ thermal ion exchange are 7.802 μ m and 0.063 μ m2/min, respectively. K+-Na+ effective diffusion coefficient in aluminum germanate glass is lower than that in phosphate glass and approximately equals to that in MP19 silicate glass, but significantly higher than those in the BK7 glass and borosilicate glass, which indicates the thermal ion-exchanged process can be controlled easily. Effective 1.2 μ m near infrared emission belonging to 5I6→5I8 transition could be observed under 644 nm pump whose the maximum stimulated emission cross-section at 1.196 μ m is derived to be 2.30×10-21 cm2. For the 5I6→5I8 transition of Ho3+, the gain cross-section achieves a magnitude of 10-21 cm2 when fraction factor P exceeds 0.6. Effective near-infrared fluorescence and perfect waveguide performance demonstrate that Ho3+ doped aluminum germanate glass is a kind of potential gain medium in~1.2 μ m waveguide laser device.关键词：Ho3+ ions;K+-Na+ thermal ion-exchanged;aluminum germanate waveguide glasses;near-infrared emission133|40|1更新时间：2020-08-12
- 摘要：In order to enrich the diversity of patterns in dielectric barrier discharge system, two water electrodes were used as a device in dielectric barrier discharge system. The whole cell is placed into a big chamber which contains a mixture gas of argon and air inside(argon content χ=25%). We found the honeycomb hexagon pattern with halo firstly. The pattern taken by an ordinary camera was composed of center spots, halos, and honeycomb framework. Center spots were located at the center of the halos, and the two previous structures were located at the center of the honeycomb framework. The spatio-temporal structure of pattern can be investigated by an intensifed charge-coupled device(ICCD) camera with three-channel. Results show that the discharge sequence of the honeycomb hexagon pattern with halo is halos-honeycomb framework-central spots in each half voltage cycle. The spatio-temporal structure of the pattern can be investigated with photomultipliers(PMT). Results show that the discharge of halo is locally selective in time and space. The molecular vibrational temperatures of three sub-lattices are calculated using the spectral lines of the N2 second position band(C3Πu→B3Πg).Results show that the molecular vibrational temperatures of the center spots are 2 632 K, the molecular vibrational temperatures of the halos are 2 679 K, the molecular vibrational temperatures of the honeycomb framework are 2 720 K. In this paper, the wall charge theory is used to explain the formation mechanism and spatio-temporal structure of honeycomb superlattice pattern with halo.关键词：DBD;honeycomb superlattice pattern with hole;spatio-temporal dynamics;wall charges161|185|2更新时间：2020-08-12
- 摘要：Upconversion materials of YF3:Er3+,Yb3+ doped with Al3+, Ba2+ were prepared by high temperature solid state method in order to enhance emission intensities in the field of laser anti-counterfeit. Al3+ and Ba2+ could cause host lattice shrinking, reduce local crystal field symmetry around rare earth ions, increasing the intra 4fN transition probabilities. The 548 nm green and 660 nm red emission intensities of samples doped with 1.7%Al3+ (mole fraction) were 1.1 and 1.4 times as strong as the ones without Al3+ respectively according to upconversion emission spectra under 980 nm excitation. The green and red emission intensities of samples doped with 0.8%Ba2+ (mole fraction) were 2.8 and 2.2 times as strong as the ones without Ba2+ respectively. The Ba2+ contents had effects on crystal phases with X-ray diffraction (XRD). The results of differential thermal analysis (DTA), emission spectra, XRD, scanning electron microscope (SEM) showed that optimal sintering temperature was 955℃ where optimal luminescence properties, crystallinities, grain growth appeared for samples with the optimal doping contents. Luminescence mechanisms of 548 nm green and 660 nm red emissions were discussed with fluorescent lifetime curves and fitting results of upconversion emission intensity and excitation current. Energy level transition processes were represented for YF3:Er3+,Yb3+ materials under 980 nm excitation.关键词：upconversion;YF3;high temperature solid state;Al3+;Ba2+110|117|1更新时间：2020-08-12
- 摘要：The surface and electrical characteristics of the bare poly(vinyl alcohol)(PVA) and PVA modified with cross-linked poly(methyl methacrylate)(C-PMMA) by 1,6-bis(trichlorosilyl)hexane(C6-Si)(C-PMMA/PVA) were studied. The surface roughness increases from 0.386 nm to 0.532 nm, and the capacitance drops to 11.5 nF/cm2 from 14.2 nF/cm2 by the cross linking, however, the contact angle of water is greatly raised from 36° to 68°, indicating that the surface polarity of PVA is remarkably decreased by the modification of C-PMMA. Additionally, the leakage current of the C-PMMA-modified PVA layer is reduced by about 2 orders of magnitude. The C-PMMA/PVA as well as bare PVA insulating layers are utilized to fabricate organic field-effect transistors(OFETs) based on 3-hexyl thiophene (P3HT) with a bottom gate/top contact configuration. The performance of the device with the C-PMMA/PVA insulating layer is significantly improved, with the on/off ratio increased by 20 times and the mobility increased by 4 times, reaching~102 cm2·V-1·s-1and 3.3×10-2 cm2·V-1·s-1, respectively. Furthermore, the hysteresis of the P3HT OFET, which mainly originates from the high surface polarity of the PVA insulating layer, is reduced dramatically by the modification of a very thin C-PMMA film.关键词：interface modification;cross linking;OFETs;hysteresis158|569|1更新时间：2020-08-12
- 摘要：A new compensation structure for active matrix organic light emitting diode (AMOLED) display using indium-gallium-zinc-oxide (IGZO) thin film transistors (TFTs) was proposed. It featured adopting the data line to turn off controlling transistor between the power supply and the driving transistor to suppress leakage current during the programming time. Comparison of circuit performances was carried out between the proposed circuit and the conventional ones. It is proven that the proposed pixel circuit can efficiently compensate threshold voltage shift and mobility variations of the driving transistor. And IOLED discrepancy can be decreased to be less than 5% and 9%, with VTH shift of 2 V and mobility increasing of 30%, respectively. Furthermore, as simultaneous driving method is used, the minimum required programming time is derived in details. The programming ability and mechanism of the proposed pixel circuit are well proven by discrete field-effect devices using FPGA platform. Although the proposed pixel circuit has much simplified driving structure, it has improved compensation accuracy.关键词：AMOLED;IGZO-TFTs;threshold voltage;pixel circuit136|164|0更新时间：2020-08-12
- 摘要：In order to verify the feasibility of preparing Cu2SnS3 (CTS) thin films and solar cells by hybrid sputtering single metal target and chalcogenide targets, CTS precursors were deposited on Mo-coated SLG substrate by magnetron sputtering Sn and CuS targets. Then, the precursors were alloyed at low temperature and sulfurized at high temperature sequentially to form CTS films. Meanwhile, the effects of different heating rate during sulfurization on CTS morphology were investigated. Structural, morphological, compositional and phases features of the films were investigated using X-ray diffraction(XRD), scanning electron microscope(SEM) equipped with an energy dispersive X-ray spectroscopy(EDS), Raman spectroscopy(Raman), respectively. Meanwhile, the optical-electrical properties of the films were characterized by UV-Vis-INR and Hall measurement system. Finally, monoclinic structure of CTS thin film with pure phase, smooth and compact surface was obtained under a condition of heating rate of 35℃/min during sulfurization process. Then, the current-voltage (I-V) of the solar cells was carried out under the standard test conditions(AM1.5, 100 mW/cm2, 300 K) using a Keithley 2400 sourcemeter. The conversion efficiency of the fabricated CTS film solar cells was 1.18% with an open-circuit voltage of 299 mV, a short-circuit current density of 16.6 mA/cm2. In conclusion, it is expected to fabricate high efficient CTS thin film solar cells by magnetron sputtering single metal target Sn and chalcogenide targets CuS.关键词：Cu2SnS3 (CTS) thin film;magnetron sputtering;sulfurization;solar cells111|202|0更新时间：2020-08-12
- 摘要：Due to the high toxicity and bioaccumulation of cadmium in organisms and environment, it will cause great harm to the human body and the environment. Therefore, it is necessary to determine the concentration of cadmium in the natural environment. In this study, a new method for the determination of trace cadmium(Ⅱ) in environmental water samples was established based on the resonance Rayleigh scattering and resonance nonlinear scattering of the cadmium(Ⅱ)-protein-congo red system. In pH=4 BR buffer solution, cadmium(Ⅱ) reacts with bovine serum albumin solution and congo red solution to form a ternary ion-associated complex, which can greatly enhance the resonance Rayleigh scattering (RRS), second-order scattering (SOS) and frequency doubling scattering (FDS) signals of the system. The maximum scattering wavelength locates at 560 nm (RRS), 690 nm (SOS) and 352 nm (FDS), respectively. Under the optimum conditions, enhanced peak signal (ΔI) has good linearity with the concentration of cadmium(Ⅱ) within a certain range. The detection limits are 0.31 μg/L (RRS), 0.29 μg/L (SOS) and 0.34 μg/L (FDS) respectively. The method is applied to the determination of cadmium(Ⅱ) in laboratory wastewater, Fujiang River water and Nongfu Spring with recovery rates between 93.2% and 107.7%, and the relative standard deviations (RSD) are 0.8%-3.1%. The results are satisfactory.关键词：cadmium(Ⅱ);resonance Rayleigh scattering;resonance nonlinear scattering;environmental monitoring;cong red142|329|0更新时间：2020-08-12
- 摘要：Formation and property of guided modes were studied numerically in thin layer waveguide induced by photorefractive surface waves under diffusion nonlinearity. By employing the split-step Fourier method, the propagation of the guided modes were simulated. By solving the guided modes, the guiding properties of photorefractive surface wave-induced thin layer waveguide were analyzed. The orders and propagation waveform of guided modes can be controlled by adjusting the values of propagation constant and guiding parameter. With the increase of orders, the profile of the guided modes becomes more and more asymmetric. The peak amplitude of the guided modes increases monotonically with the guiding parameter. The energy of the guided modes is mainly concentrated in the thin waveguide near the -c axis of photorefractive crystal and becomes from small to large with an increase of the propagation constant. The stability properties of the guided modes are investigated numerically and it is shown that they can be stable.关键词：nonlinear optics;photorefractive surface wave;thin layer waveguide;guided modes133|172|0更新时间：2020-08-12
- 摘要：Au nanorods(NRs) wrapped with SiO2 shells(Au NRs@SiO2) were doped into the active layer of organic solar cells(OSCs). With these Au NRs-induced surface plasmon resonance effect to promote the light absorption of the active layer, power conversion efficiency(PCE) was significantly enhanced in our OSCs. The effects of both doping concentration of Au NRs and thickness of SiO2 shells on device performances were explored. The analysis results demonstrate that the best performing PCE is as high as 4.02% with 1.5% doping concentration of Au NRs, while its value can be further improved to 4.38% with an optimal SiO2 shell thickness of 3 nm, showing a large enhancement factor of 29.2%.关键词：organic solar cell;surface plasmon;Au nanorods wrapped with SiO2123|49|2更新时间：2020-08-12
- 摘要：The 2 μm wavelength solid-state laser doped with holmium has became a research hotspot and been applied in many fields, including laser radar, laser ranging, electrooptical countermeasures, and laser medicine, because of its output wavelength in range of atmosphere window, strong absorption band of water and safe area of eyes. Firstly, research progresses of the level system of 2 μm wavelength solid-state laser doped with holmium are summarized, as well as those popular crystals doped with holmium. Then, the progress of those lasers based on other crystals doped with holmium is given. Finally, the development of Ho-doped solid-state laser is prospected.关键词：2 μm;Ho-doped solid-state laser;Ho-doped crystals182|88|4更新时间：2020-08-12
- 摘要：A practical method of a high optical power density and high power fiber-coupled laser diode module based on six single-emitter semiconductor laser diodes at 915 nm/974 nm was demonstrated by ZEMAX software simulation and experiments. To obtain a high power and high optical power density laser beam, which included two wavelengths for pumping two kinds of solid lasers or fiber lasers by the same module, the optical reshaping, spatial multiplexing and wavelengths multiplexing were used in this module to combine six single emitters into a single beam. Then, an aspheric lens was used to couple the combined beam into an optical fiber. This module can produce more than 46 W output power with coupling efficiency of 83% from a standard multi-mode optical fiber with core diameter of 105 μm and numerical aperture(NA) of 0.22.关键词：semiconductor laser diode;fiber coupling;wavelength multiplexing;ZEMAX156|187|0更新时间：2020-08-12
- 摘要：In order to explore the temperature field distribution and power density threshold of 1 064 nm laser that irradiate film and make it phase change in 100 s, and to compare the difference between the transmittance modulation characteristics in the near infrared and mid-infrared band, a model of laser irradiation was set up and the temperature field was simulated. Then, the 1 064 nm laser transmittance response characteristic with time was tested in the front and back face of VO2 film with different laser power density in 100 s separately. VO2 thin films in the experiment were prepared by molecular beam epitaxy on Al2O3 substrate. Simulation results show that the film reaches the phase-transition temperature in 1 ms with 25 W·mm-2 laser power density. It is found that the laser power density threshold is 4.1 W·mm-2 and 5.39 W·mm-2 when irradiating the front and back face of the VO2 thin film with 50 nm thickness respectively. The transmittance modulation depth of 1 064 nm is approximately 13% of VO2 thin films with 30 nm thickness. However, compared with 62% for 3 459 nm laser, the transmittance modulation characteristic in near infrared is not obvious for VO2 thin films.关键词：VO2 thin films;molecular beam epitaxy;COMSOL simulation;temperature field distribution;transmittance modulation depth;phase transition power density threshold118|100|1更新时间：2020-08-12
- 摘要：For NH2CH=NH2PbI3 (FAPbI3) photodetectors, the challenges are that the high annealing temperature (150-160℃) for pure α-FAPbI3 perovskite are not suitable for flexible substrates and the transition from α to δ phase makes the photodetectors unstable in air at room temperature. In this paper, we synthesized pure α-phase FA1-xCsxPbI3 perovskite by doping Cs at an annealing temperature of 100℃ and fabricated FA1-xCsxPbI3 photodetectors. The devices exhibit best performance and air stability. At -0.5 V, a high on/off current ratio of 1.6×105 and fast response times of 7.1 μs are obtained, and the specific detectivities are above 1012 cm·Hz1/2·W-1(Jones) over a broad spectral range from 350-800 nm.关键词：FAPbI3 perovskite;phase transition;Cs-doped;performance of photodetector176|151|1更新时间：2020-08-12
- 摘要：In order to increase the wavelength tuning range of the tunable laser and improve the reliability and stability of the system, a wavelength tunable vertical cavity surface emitting laser with a central wavelength of 852 nm was designed based on the characteristics of electrically controlled birefringence of liquid crystal. The physical principle that the structure obtained a wide range of wavelength tuning and single polarization stable output was analyzed, and the reflection spectra corresponding to the thickness of different liquid crystal layers under the whole device were further calculated by the transfer matrix method, the lasing wavelength of laser with different thickness and refractive index of liquid crystal was obtained. The results show that the tuning range of the liquid crystal tunable laser with single polarization reaches 31 nm and the tuning efficiency is more than 10 nm/V.关键词：lasers;tunable semiconductor laser;liquid crystal;transmission matrix theory;wavelength tuning range149|218|3更新时间：2020-08-12
- 摘要：Due to the low efficiency, long detection time, and lack of visual results show of the quality monitoring of cigarette products, the near infrared spectroscopy analysis techniques were applied to the process of product stability control and a new feature extraction method of the fingerprint spectrum was presented. Firstly, the principal component analysis method was used for the dimension reduction of the near infrared (NIR) spectra, and the radar chart was employed for the visual description of the quality stability trends of the products. This ensures the unification of integrity and fuzziness of the spectra data. And then, the barycentre features of the radar chart were extracted, which realized the demonstration of the internal structure of the samples. Also the model of the quality stability and the abnormal type was established. The study shows that this feature extraction method achieves desired result and can be used in the quality monitoring and counterfeit identification of the cigarette products.关键词：products quality stability;principal component analysis;radar chart;feature extraction of barycentre;near infrared spectroscopy136|142|3更新时间：2020-08-12
- 摘要：SERS and SEF technology with sliver nanoparticles can achieve very high sensitivity, thus it can be used to analysis biological samples. Here, a technique was reported, which can be used to improve detection results of SYBR GreenⅠ by SERS and SEF at the same time by using silver nanoparticles in microchannels. The fundamental and enhancement effect of this method were studied. First, the excimer laser was used to write directly on the PMMA substrate to etch the microchannel with the width of 200 μm and depth of 68 μm. The prepared silver precursor solution was then added to the microchannel. The surface enhanced Raman(SERS) and surface enhanced fluorescence(SEF) substrate were prepared by heating. Next, the Raman and fluorescent signals were compared with and without adding silver nanoparticles. Besides, the effect of silver nanoparticles on the Raman and fluorescent signal enhancement of SYBR GREEN I in micro-channel was studied. The results show that the enhancement factor of the surface-enhanced Raman(SERS) experiment with silver nanoparticles is 3.5×103. The intensity of the fluorescence signal of the samples with silver nanoparticles increases by about 1 time compared with that of the fluorescent signal without silver nanoparticles. When SYBR Green Ⅰ is detected in the microchannel, it significantly increases the Raman and fluorescent signals by adding silver nanoparticles. It can be used in microfluidic chip technology with SYBR GreenⅠ dye.关键词：surface enhanced fluorescence;surface enhanced Raman;microfluidic chip;optical detection;SYBR GreenⅠ165|285|1更新时间：2020-08-12
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Flame Spectral Characteristics and Analysis of Combustion Kinetics at Initial Stage of Gasoline Fire
摘要：In order to realize the timely warning of oil fires, the characteristics of flame spectra in the early stage of 92# gasoline combustion were experimentally studied to explore the identification and prevention of fire based on spectral technology. The molecular and free radicals with characteristic peaks in the flame were analyzed as well as their formation mechanism. The distribution of flame characteristic spectrum was shown, and the reasons for strong and weak spectra of different bands were explained. In addition, the combustion process was analyzed based on the change of spectral intensity of the groups. The results show that molecules and free radicals that are suitable for the recognition of gasoline fire at the initial stage of combustion are C2-512.9, 547.0, 516.5 nm band, CH-431.4 nm band, H2O-927.7, 933.3 nm band. Spectral characteristics mainly occurred in the visible region and near-infrared region, little in near-ultraviolet region. Group is not easy to accumulate in the initiation and transfer stage of chain reaction, so the according spectral intensity is relatively small. However, some groups are able to accumulate in the chain branch and interrupt stage, thus the spectral intensity is relatively large. The characteristic spectral intensity of molecules and free radicals will change with the combustion process. When combustion reaches the stable stage, its unique characteristics disappear.关键词：gasoline;initial stage of fire;flame spectrum;characteristic band;combustion kinetics114|259|2更新时间：2020-08-12
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