摘要:The detection of stimulated bioluminescence is the new technology and method of target detection in water.Three representative luminescent alga,such as lingulodinium polyedrum,pyrocystis noctiluca and pyrocystis lunula,are studied.The platform of stimulated bioluminescence is built by the use of spectrometer,photon counter,Couette flow device and so on.The optical characteristics of bioluminescence stimulated by flow are researched.Based on the experimental study,probabilistic and mathematic statistic theory,the math-physical model of stimulated bioluminescence is built.The experiment results showed that the light spectrum of luminescence alga is a single wavelength with about 472 nm of the maximum wavelength and 30~40 nm of full width at half maximum.Furthermore,the intensities of bioluminescence are different with different organisms and attenuated with the decrease of the energy of organisms,but it will be recovered after a rest.On the basis of their bioluminescence response in the same stimulated condition,these species were ranked in order of decreasing sensitivity as I(pyrocystis lunula)>I(pyrocystis noctiluca)>I(lingulodinium polyedrum).
关键词:stimulated bioluminescence;luminescent alga;Couette flow;math-physical model
摘要:SiO2 single crystals that irradiated with 600 keV,4 MeV and 5 MeV Kr ions were investigated in 320 kV high voltage Experimental Platform (IMP,Lanzhou) by infrared spectra and fluorescence spectroscopes.In the low-energy region,single ion tracks are well separated and the damage process is dominated by the formation of simple color centers such as F2 centers.For the high energy ions,the energy density in ion tracks produced at high stopping power is larger,and consequently the defect concentration increases significantly.At higher defect densities,the distance between single defects is smaller facilitating aggregation of individual electron centers to defect clusters and also defect annihilation by recombination of hole and electron centers.The latter process determines the limited efficiency of color-center creation under heavy-ion irradiation.Using the unified thermal spike model,it is possible to fully describe the experimental data,which clearly demonstrate a synergy between the nuclear energy loss and the electronic energy loss.
关键词:heavy ion irradiation;color centers;PL spectra;thermal spike
摘要:A novel high work-function (WF) transparent conducting oxides,lanthanum titanate (LaTiO3)-doped indium oxide (ILTO),with notable electrical and optical features,synthesized by a double electron beam evaporation associated with End-Hall ion assisted deposited technology is introduced.Its room-temperature ultraviolet photoluminescence (PL) with a peak at around 386 nm are determined.A high WF near 5.20 eV is determined for the as-deposited ILTO samples.As far as we know,this is the first report on PL emission at room temperature as well as high-WF properties in a multi-doping transparent oxide semiconductor.The effects of high WF afford more opportunities to develop and optimize the performance of organic photoelectric devices,and facilitate the fabrication process of devices.
摘要:α-TeO2[DK]∶Ho3+,Yb3+,α-TeO2[DK]∶Tm3+,Yb3+ and α-TeO2[DK]∶Tm3+,Ho3+,Yb3+ nanoparticles were prepared via a hydrothermal process.Under 980 nm excitation,α-TeO2[DK]∶Ho3+,Yb3+ nanoparticles showed green (545 nm) and red (651 nm) emission,which were attributed to the 5S2 → 5I8 and 5F5→ 5I8 transitions,respectively.The upconversion emission color changed markedly from yellow to green when the mole fraction of Yb3+ ions changed from 5% to 15% due to the green emission at 545 nm increased.The α-TeO2[DK]∶Tm3+,Yb3+sample showed blue emission at 476 nm,which was attributed to the 1G4→3H6 transition,and two weak red (651,675 nm) emissions,which were attributed to the 1G4→3F4 and 3F2→3H6 transitions,respectively.The relative intensity ratio of the blue emission to the red emissions increased gradually with increasing Yb3+ concentration.Based on the generation of blue,green and red emissions,the α-TeO2[DK]∶Tm3+,Ho3+,Yb3+ nanoparticles could compose different color,including white,by controlling the doping concentration of rare earths in the α-TeO2 nanoparticles.
摘要:Nanoparticles NaYF4:Tb3+,Er3+ with hexagonal phase were synthesized by hot solvent method and the influences of synthesis conditions on the formation and size of particles were also analyzed.The reaction temperature is the dominate condition.The results confirm that some conclusions that the hexagonal phase is thermodynamically more stable and a more orderly structure.It is found that with the nano-size decreasing,the conversion efficiency is significantly reduced.NaYF4:Tb3+,Er3+ nanoparticles with core/shell structure were prepared to analyze and compare further.It is indicated that the luminescence of the NaYF4:Tb3+,Er3+ particles with core/shell structure were enhanced significantly due to the reduced surface defects and the suppressed excitation energy quench.
摘要:(Ba0.75Sr0.25)TiO3 thin film was prepared by sol-gel process.The phase structure,photoluminescence properties and optical transmittance of the films annealed at different temperature were studied respectively.The results show that a strong photoluminescence phenomenon can be observed under blue light excited at room temperature.The emission band is from 500 nm to 650 nm,and the peak is about 525 nm.An enhanced intensity of photoluminescence property was measured by increasing the anneal time for amorphous films.Moreover,the photoluminescence intensity also increases with the film thickness.A weak photoluminescence peak was observed in crystalline film.In addition,both the crystalline and amorphous films have good optical transmittance in the visible light region.
摘要:The transparent oxyfluoride glass ceramics containing GdF3 nanocrystals were prepared by high-temperature melting and heat treatment method.Comparison with the as-prepared glass,Dy3+ doped oxyfluoride glass ceramics exhibit higher emission intensity excited at 386 nm and the intensity ratio between blue light and yellow light emission increases gradually with the heat treatment temperature,which indicates that Dy3+ ions have participated into the precipitated GdF3 nanocrystals.Under the excitation of 980 nm laser diode,the upconversion luminescence intensity increases gradually with the heat treatment temperature and the upconversion luminescence peaks appear apparent Stark splitting phenomenon,which also demonstrates Er3+ ions have entered into the precipitated GdF3 nano-crystalline phase.Based on the relationship between excited power and the upconversion intensity in Er3+,Yb3+ doped glass ceramic GC-650,two-photon absorption process was determined for the green upconversion emission of Er3+.
摘要:GaN thin films were prepared by changing the growth condition.The epitaxial layers were grown by metal-organic vapor phase epitaxy on sapphire (0001) substrates,and were characterized by photoluminescence,optical microscope and X-ray double crystal diffraction.In the experiment,we used full width at half maximum of X-ray double crystal diffraction to detect the dislocation density,and found the samples dislocation density was lowest when TMGa flows at 70 cm3/min.Using the best value of TMGa flows,we grew the samples by changing the growth temperature.Photoluminescence spectra showed that higher growth temperature is conducive to improve the optical properties,reduce the Ga vacancies density in the GaN samples,and improve the quality of GaN crystal.Optical microscope test indicated that the increasing of the growth temperature will improve the surface morphology,it gives the same conclusion with photoluminescence spectra test.
关键词:metal-organic chemical vapor deposition(MOCVD);non-doped GaN;double-crstal X-ray diffraction;photoluminescence spectra
摘要:AlN films were prepared by DC reactive magnetron sputtering,and the effects of deposition conditions and GaN buffer layers on their qualities were also investigated.The crystal structure and surface morphology of films were characterized by X-ray diffractometer (XRD) and scanning electron microscopy (SEM).The XRD results show that low pressure,short target-to-substrate distance and appropriate N2 partial pressure can facilitate the (002) preferential orientation AlN films.With the increase of deposition time the full width half maximum of (002) diffraction peak for the films deposited on 50-nm-thick GaN buffer layers decreases drastically,but it was nearly unchanged for AlN films deposited on 1-μm-thick GaN films.The SEM measurements reveal that the grain size distribution of AlN film deposited on 1-μm-thick GaN films is much uniformer than on 50-nm-thick GaN buffer layers in the early stages of deposition,and with the increase of deposition time their grain size distributions can nearly reach the same.
摘要:White organic light-emitting diodes based on three small molecular fluorescence materials were designed and prepared.The emitting layers consisted of a red dye,4-(dicyanomethylene)-2-tert-butyl-6-(1,1,7,7-tetra-methyljulolidin-4-yl-vinyl)-4H-pyran (DCJTB),doped in a green layer of 8-hydroxyquinoline aluminum salt (Alq3),which further formed a heterojunction with a blue layer of 2,2'-(1,3-phenylene)-bis (OXD-7).N,N'-bis-(naphthalene-1-yl)-N,N'-bis(phenyl)-benzidine (NPB) was used as a hole transport layer.Voltage dependent emission spectra and their colorimetric characteristics were manipulated using different device structures.After adjusting the carrier injection/transporting properties,the exciton recombination region was confined and the color stability was improved against the driving voltages.An improved white light-emitting device has a wide spectrum in visible range and a good color stability,its color coordinates change slightly from CIE(x,y)=(0.364,0.314) to CIE(x,y)=(0.332,0.291) when the driven voltage changes from 9.1 V to 12.9 V.
摘要:A novel structure of green phosphorescent organic light-emitting diode was fabricated.The structure of the devices was ITO/HAT-CN(x nm)/MoO3(30 nm)/NPB(40 nm)/TCTA(10 nm)/CPB:GIr1(30 nm,14%)/BCP(10 nm)/Alq3(25 nm)/LiF(1 nm)/Al(100 nm),in which X was 0,8,10,12,14,15 nm,respectively.The current density-voltage-luminance(J-V-L) performance shows that this structure is beneficial to the reduction of the driving voltage and the enhancement of the luminance.It was found that the best thickness was 12 nm HAT-CN layer,the highest luminance of the device was 32 480 cd/m2 at 15 V,the turn-on voltage of this device was 3.5 V and the current efficiency was 24.2 cd/A.Hole-only device was fabricated to verify the enhancement of hole injection and transport properties of this structure.
摘要:This paper presents a kind of axially filling-factor graded 2D triangular lattice air holes photonic crystals.The PC is periodically composed of conical holes.The size of air holes continuously changes along the axis of air holes.The filling-factor changes from 0.700 to 0.866.Simulation results show that in range of normalized wavelength (λ/a) 1.43~2.71 and 3.41~4.00,the horizontal incident light is deflected to the bottom of photonic crystals as well as the small filling rate part.The sample has the function of splitting light.And axially filling-factor graded 2D triangular lattice air holes photonic crystals are prepared on p-Si(100) wafers by electrochemical etching and MEMS technique,the filling rate ranging from 0.800 to 0.866.
摘要:A large-microfluidic-channels,near-panda micro-structured optical fiber (MOF) sensor is designed by silver nanowires localized surface plasmon resonance.Optical field distribution of the fiber at a certain wavelength is calculated and simulated using the finite element method (FEM) under the boundary condition of anisotropic perfectly matched layer (PML).The effects of the refractive index,diameters of silver nanowires on the confined loss and the sensitivity are discussed,respectively.The results show that both the confined loss and the spectral peak wavelength increase when the refractive index of analyte increases.The confined loss,the spectral peak wavelength,the change in the spectral peak wavelength and the sensitivity increase with the diameters of silver nanowires.Furthermore,the double spectral peak wavelength will emerge when the diameters of silver nanowires increases to a certain size.At last,the maximum amplitude sensitivity 910 dB/RIU and the maximum spectral sensitivity 1 400 nm/RIU are obtained when the diameters of silver nanowires is equal to 150 nm.
关键词:fiber and waveguide optics;microstructure fiber;surface plasmon resonance;optical fiber sensor;refractive index
摘要:GZO transparent conductive layers were deposited on p-GaN surface by magnetron sputtering.AgOx thin films were inserted between p-GaN and GZO to improve the performance of LED devices.The AgOx/GZO thin film exhibited low resistivity (5.8×10-4 Ω·cm) and high transmittance (above 80% in visible range) after nitrogen annealing.The AgOx interface insertion layer could effectively reduce the contact barrier,leading to good Ohmic contact characteristics of GZO/p-GaN and improved photoelectric performance of LEDs.With 50 mA injection current,the forward voltage reduced from 9.68 V to 6.92 V and the luminous intensity increased by 13.5% compared with conventional GZO electrode LEDs.
摘要:GaN-based blue light-emitting diodes were applied bias of-400,-800,-1 200 and-1 500 V electrostatic discharge in human body mode.The electrical and optical parameters of LED were characterized before and after electrostatic discharge stressing with the theoretical analysis of the influence of electrostatic on LED reliability.After human body mode static crack down on the GaN-based blue LED,the I-V characteristic curve changed,the luminous flux reduced,LED's degradation rate was also accelerated.It is deduced that the LED was hit by electrostatic generates secondary defects and melting channel inside the chip.Based on the result of I-V characteristic curve at different temperature,we assumed that the shallow level ionization is dominated in LED,while after static crack down,the deep level ionization is dominant.Therefore,a failure mechanism caused by electrostatic can be deduced as follow.The generation of secondary defects and melting channel,the shallow level/deep level carrier movement and the change of radiative/non-radiative recombination,cause the degradation of LED performance.These find make great efforts to understand the failure mechanism caused by the electrostatic discharge and anti-static design.
摘要:A narrow-linewidth tunable laser based on a unique dual-lens external-cavity structure was reported,in which a thermally-tuned 50 GHz etalon was utilized to provide standard ITU-grid wavelengths and a PZT-actuated tunable Fabry-Pérot filter to select wavelength.In experiment,the laser wavelength could be tuned from 1 525 to 1 580 nm,covering the whole C band.And it measured a linewidth of 37.5 kHz,an output power >50 mW at the 400 mA pump current,a SMSR > 50 dB and a tuning speed <3 ms.The performance is superior to the requirements of coherent communication applications and the reported planar waveguide-based counterparts.Moreover,the dual-lens structure bears other merits such as high positioning tolerance and potential for ultra-narrow linewidth.It may have a wide application after miniaturization and standard packaging.
摘要:Since the pulse duration of femtosecond and sub-picosecond laser are quite short,the electrons and lattice in material cant couple in time when the sample is irradiated by ultra-short pulse laser.According to critical-point phase separation (CPPS) theory and actual laser ablation process,the thermal conductivity in the model can be restricted regionally.Based on aforementioned analysis,an optimized two temperature model (TTM) is formulated,which provides a new perspective into the energy transport process during ultrashort single pulse laser ablation.Using finite element analysis (FEA) software,a model which exhibits the cuprum film sample irradiated by ultrashort pulse laser is proposed.Taking account of symmetrical spatial shape of Gaussian distribution laser on the sample,part of the model is used to calculate simply.According to calculation,the electron-lattice coupling and thermal conduction transient parts in the optimized TTM are analyzed separately.The results indicate that,during ultra-short laser irradiating on cuprum film,the coupling item can be neglected,but the conduction item cant be neglected.The conduction item plays a major role during femtosecond and sub-picosecond laser irradiating on cuprum,while the electron-lattice coupling item plays a major part after laser's effect.With finite element method (FEM),the optimized 1D and 2D TTM model are calculated.For the purpose of ablating sample,suitable laser pulse fluence of 100 fs,300 fs,1 ps,2 ps are applied.The electron and lattice transient temperature distribution evolutions along time in the centre of laser irradiated zone are obtained.For further analysis,according to the spatial lattice temperature distribution,phase separation zone,phase explosion zone and melting zone are calculated.
关键词:ultra-short laser pulse;two temperature model (TTM);finite element method (FEM);critical-point phase separation(CPPS)
摘要:The indium gallium zinc oxide (IGZO) thin films were fabricated by RF magnetron sputtering at room temperature in this paper.The crystal structure,surface morphology,and optical electrical of the IGZO films were investigated by X-ray diffraction (XRD),atom force microscopy (AFM),and photometry,respectively.The results revealed that the IGZO film was amorphous,the surface of the films was uniform and smooth.A good optical transmittance of over 80% was obtained in the visible light.The IGZO thin film transistors were successfully fabricated at low temperature (<200℃) using the room temperature sputtering IGZO thin film as the active layer.The field effect mobility of a-IGZO TFT was larger than 6.0 cm2·V-1·s-1.The device's on/off ratio was 107,threshold voltage was 1.2 V and subthreshold voltage swing is 0.9 V/dec.Constant bias stress testing showed that the a-IGZO TFT threshold voltage exhibited positive shifts as time increased.
摘要:The interaction between rare earth ion Y3+ and bovine serum albumin(BSA) was studied by fluorescence spectrum and ultraviolet-visible absorption spectrometry.It was shown that Y3+ has a quite strong effect to quench the fluorescence launching and enhance the UV absorption spectra of BSA.The maximum emission peak of BSA shifted to short wave by 20~25 nm.After the fluorescence quenching date was analyzed by Stern-Volmer equation,the results indicated that the reaction between bovine serum albumin and Y3+ generated the new complex-system.The quenching belonged to static fluorescence quenching,with non-radiation energy transfer happening within single molecule.The binding constants (KA) and thermodynamics parameters (ΔΗ,ΔS,ΔG) were calculated according to equation of fluorescence spectrometry at different temperatures.Based on thermodynamic data,the main reaction between Y3+ and BSA was van der Waals force and hydrogen bond,but electrostatic force can not be ignored.The effect of rare earth ion Y3+ on the conformation of BSA was researched by synchronous fluorescence spectrometry.
摘要:GdBO3:Eu3+ thin films were successfully prepared on porous anodic aluminum oxide (AAO) template surface with a pore size of 100 nm by using a hydrothermal process combined with high-temperature annealing.The morphology,crystal structure,and luminescent properties of the as-prepared GdBO3:Eu3+/AAO thin films were characterized.The morphologies of the as-prepared GdBO3:Eu3+/AAO thin films could be controlled through adjusting the annealing temperature.X-ray diffraction (XRD) and photoluminescence (PL) results show the as-prepared GdBO3:Eu3+ materials are vaterite-type GdBO3 phase.PL results indicate the relative intensities in 5D0→7F2 and 5D0→7F1 transitions are very sensitive to the annealing temperature,the ratio value of the red emission (5D0→7F2) to the orange emission (5D0→7F1) of GdBO3:Eu3+/AAO samples increase with the decrease of the annealing temperature.The color purity improvement of GdBO3:Eu3+/AAO thin films is obtained by decreasing the annealing temperature.