最新刊期
卷 20 ， 期 3 ， 1999
- 摘要：We have investigated the physical and chemical characteristics of 8-hydroxyquinoline aluminium-(Alq3),which has been used most widely as the electron transporting and emitting layer in organic light-emitting diodes.The fluorescent stability of Alq3 is reported when the film was irradiated by an ultraviolet(UV)lamp.Thin film was analyzed in situ by using UV-V is absorption spectrophotometer,fluorescence spectrometer,X-ray photoelectron spectroscopy(XPS)and nano-second fluorescence spectrophotometer.We observed that the PL intensities and absorbance decreased with increasing the irradiated times,the fluorescent decays were rapid after irradiation,and the X-ray photoemission spectra of the irradiated films changed.Degradation in photoluminescence properties was significant in the presence of atmospheric moisture.The photodegradation reaction was a hydrisis process involving water in air to yield the fluorescent quenchers.The results indicated that reaction between H2O in the air and Alq3 to liberate one or more 8-hydroxyquinoline at first and then undergoes a condensation reaction to generate a non-emissive compound,which plays a role as luminescence quenching center.The photodagradation of Alq3 may seriously effect on the performance of LEDs.Therefore,it is important to keep the devices from the moisture in air for protection photodegradation,resulting in enhancement of the LEDs.关键词：fluorescent degradation;Alq3;photoluminescence85|91|2更新时间：2020-08-11
- 摘要：The advantage of luminescence of the complexes of rare earth ion and organic compounds are:high intensity of luminescence,narrow wave peak,bright color,good stable character,little decline in light,hard to be oxidized,and so on.Because of these advantages,the complexes of rare earth ion and organic compounds are widely used.The fluorescence increment effect of rare earth ion and organic compounds,such as Gd3+,La3+ and Y3+,can enhance the luminescence intensity of the certer ion of complexes,and provides scientific basis of further research and use of luminescence of rare earth complex compounds.Synthesis of the iso-polynucleus by the fluorescence increment effect has become an important subject in the field.In this paper,the iso-polynucleus complexes of Eu(Ⅲ)are synthesized based on fluorescence increment effect of rare earth.The complexes are characterized by element analysis,plasma spectra,IR spectra and fluorescence spectra.It has been confirmed that the addition of Gd3+,La3+ and Y3+ can give a great improvement on the fluorescence intensity of center Eu3+ in the complexes and it was reduced that the centent of Eu in the complexes and production cost.The influence of acidity on luminescence and the influence of temperature on luminescence while forming the complexes are also discussed in this paper.关键词：Eu(Ⅲ)iso-polynucleus complexes;sensitizing effect;RE79|195|9更新时间：2020-08-11
- 摘要：In the early 1970's,Ibach made the low energy electron diffracting experimentation on the surface of semiconductor ZnO etc..The suface polaron in the crystals was of considerable interest.Sak,Evans and Mills studied theoretically the surface polaron in polar crystals for the first time.Evans et al.investigated the effect of bulk LO phonon on the surface polaron.Gu et al.discussed the strong,weak and intermediate coupling surface polaron in semi-infinite crystals.The properties of the surface polaron has been calculated by many methods.In fact,so far research of the surface polaron only was restricted to the approximation and calculation where the interaction between phonons of different wave vectors in the recoil process was neglected.The properties of the surface polaron,which considers the corresponding interaction,have been discussed using the perturbation method by the present authors and co-workers.In this paper,the characteristic of the surface polaron in semi-infinite crystals is studied.The effective Hamiltonian,the effective mass and energy of interaction between phonons of the surface-polaron-in semi-infinite crystals-are derived using L.L.P method.The influences of the interaction between phonons of different wave vector in the surface polaron are discussed.The Hamiltonian of the electron-phonon system can be written as(1a).For motion parallel to the x-y plane,we introduce unitary transformation U1 and U2.The ground state wave function of the system is ψ>=φ(ρ)>|0>.According to L.L.P method,we introduce(5).After some elementary calculation,the effective Hamiltonian of the surface ploaron in a plane parallel to the surface(9a),the effective mass of the surface polaron(10),the energy of interaction between phonons(11a)and the ratio of energy of interaction between-phonons and the energy of the surface polaron in x-y plane(12)are obtained.The properties of these quantities are discussed.关键词：surface polaron;interaction between phonon;effective mass86|78|0更新时间：2020-08-11
- 摘要：The surface and internal structure states of commercially available ZnS powder,twice heated powder and the ZnS:Er3+ thin film material prepared by evaporating with two boats,are measured by using X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS)and electroluminescence brightness measurement techniques.The information of the relation between the microstructure and the concentration of luminescent centers in the film was obtained.The experimental results show that the deposited polycrystalline films have a trend of preferential orientation.It was found that the high brightness of the devices may be attributed to the deposition growth of crystallites oriented in the(311),(400)directions and the existence of a higher population of erbium in trivalent charge state in these planes.This phenomenon may be explained that the energy needed for Er3+ ion to substitute for Zn2+ ion is less in higher index planes such as(311),(400)than in other planes.This provides a favorable condition for the formation of luminescence center.In addition,the electroluminescence brightness-increases-with increasing the size of polycrystalline grains in the higher index planes.关键词：electroluminescence;microcrystallite thin film;luminescent centers91|116|0更新时间：2020-08-11
- 摘要：In this paper,a new idea was presented for narrowing the size distribution of CdS nanoparticles by utilizing Cd(OH)2 selective coated and photocorrosion.At first,CdS nanoparticles were synthesized by wet chemical method.Sodium Hexametaphosphate(HMP)was used as stabilizing agent.Then,a layer of Cd(OH)2 was deposited on the surface of CdS nanoparticles.According to the theory of curve interface growth kinetics,Cd(OH)2 prior to grow on the surface of the bigger diameter CdS nanoparticles.So,controlling the amount of OH- and Cd2+,the bigger CdS nanoparticles can be selective coated by a layer of Cd(OH)2.At last,the whole colloid was irradiated by sunlight.CdS nanoparticles can be decomposed under irradiating of sunlight on the condition of oxygen.But Cd(OH)2,which deposited on the surface of CdS nanoparticles,can prevent the CdS contacting with the oxygen in the water.So,after several days,those uncoated smaller CdS nanoparticles were photocorroded.Only those coated bigger CdS nanoparticles were still in the colloid.Then,the narrowed size distribution of CdS nanoparticles was gained.This idea was confirmed by the study of PL spectrum of CdS nanopaticles.After selective coated by Cd(OH)2,the CdS nanoparticles' PL spectrum appears two peaks.The peak of high energy comes from the emission of bandedge of coated bigger CdS nanoparticles.The peak of low energy comes from the emission of surface state of uncoated smaller nanoparticles.During the irradiating by sunlight,the peak of the emission of surface state is disappearing gradully.But the peak of the emission of bandedge is still existent.关键词：nanoparticles;size distribution;selective coated;photocorrosion103|61|0更新时间：2020-08-11
- 摘要：Surface alignment of liquid crystals(LCs)on treated polymer substrates is one of key technologies to fabricate liquid crystal displays(LCDs)and thus many works on this subject have been done.Recent process of photo-alignment control of LC molecules on photopolymer film was considered the photo-alignment technique is a hopeful candidate for rubbing-free technique.The process of photochemical reaction of Cinnamate material 2-(cinnamoyloxy)ethyl methacrylate(CEMC)using LPP(linear polarized photopolymerization)method by UV-light was studied in this paper.We also investigated the effect of the CEMC aligning on liquid crystal LC-6710A molecules.The liquid crystal molecules alignment was more homogeneous when the photosensitive IRG184 was taken a part into pre-polymer CEMC mixture.The photochemical reaction probability was increased because of the energy transfer between photosensitive IRG184 and pre-photopolymer CEMC molecules.The change of alignment substrate surface,which was shown less difference on the micrography of substrate surface was observed before and after photochemical reaction by Atomic Force Microscopy(AFM).The pretilt angle 0.7 degree of LC molecules on photo-alignment substrate surface was measured.The electro-optical property and time response curves of twisted nematic liquid crystal display(TNLCD)with single side photo-alignment substrate were obtained.It is shown that the properties curves of TNLCD with single side photo-alignment substrate and conventional TNLCD were similar.The mechanism of liquid crystal molecule alignment on photo-alignment substrate surface was discussed.We consider that the liquid crystal molecules alignment was not ascribed to the grooves on the substrate surface,but was ascribed to the interaction between liquid crystal molecules and photopolymer molecules on substrate surface.The photopolymer material CEMC is feasible for LCD fabrication.关键词：photo-alignment;photochemistry;liquid crystal;alignment107|72|2更新时间：2020-08-11
- 摘要：Dy3+-doped fluorozirconate(ZBLAN)glasses were prepared,and the absorption and emission spectrum of Dy3+ ions in ZBLAN glasses were measured.Using Judd-Ofelt theory,parameters of Dy3+ ions in fluorozirconate glasses according to the absorption spectrum and the emission cross of 6F11/2-(6H9/2)→6H15/2 tranbsition of 1.3μm emission were calculated Ω2=3.29×1020cm2,Ω4=1.56×1020cm2,Ω6=2.48×1020cm2;and σe=0.62×10-20cm-1.The calculated results showed that ZBLAB glass is a good host for Dy3+ ion doped,and higher emission cross of Dy3+ than Pr3+:ZBLAB give a good promising for Dy3+ as the doped ion in 1-3μm fiber amplifier.The effect of the Dy3+ concentration on the emissiion intensities has been discussed,emission intensities of Dy3+ ions become stronger with incresaing the doping concentration.Concentration quenching will occur when concentration of Dy3+ exceeds 1.5mol%.关键词：fluorozirconate glasses;Dy3+ ions;optical properties90|68|1更新时间：2020-08-11
- 摘要：The effect of InAlAs deposition thickness on the areal density,size,uniformity and spatial distribution of self-organized In0.65Al0.35As/Al0.5Ga0.5As quantum dots was studied,grown on(001)GaAs substrate by molecular-beam epitaxy(MBE).The progression of surface morphology of In0.65Al0.35As quantum dots is investigated in detail by atomic force microscopy(AFM).A high density,small size,red-emission self-organized In0.65Al0.35As quantum dots have been obtained.The self-organized In0.65Al0.35As quantum dots density and average size are found to increase with increasing the InAlAs deposition thickness.Moreover,the increase of dots density is slow,compared with the variance of InAs/GaAs quantum dots with InAs deposition thickness,this might be beneficial for the realization of low-threshold quantum dot lasers since both quantum confinement and gain region are increased.It was found that the surface diffusion of Al atoms is an important factor in determining the structural properties of In0.65Al0.35As quantum dots.We believe that the Al atom of the smaller surface migration range plays a large role in determining In0.65Al0.35As quantum dots nucleation sites.The low-temperature photoluminescence(PL)from the recombination of carriers in the buried In0.65Al0.35As/Al0.5Ga0.5As quantum dots is observed 1.701eV-energy position,its linewidth is determined principally by the lateral size of dots through investigating the distribution of dots size.106|122|1更新时间：2020-08-11
- 摘要：It was found that Mn2+ may occupy(Mn2+)sub and(Mn2+)--int-sites by luminescence and excitation spectra.EPR measurements support this conclusion.(Mn2+)sub,(Mn2+)int and nclusters were identified.The g factor and HFS constants increases with decreasing the diameters of the nanocrystals.It might be due to the hybridization between sp and d states by quantum confinement effects and the surface states.关键词：nanocrystals composites;EPR spectra;g factor and HFS constant140|101|1更新时间：2020-08-11
- 摘要：Undoped and Mn2+-doped ZnS superparticles about 5nm size-have been prepared and self-activated luminescence(SA)observed in aqueous and ethanol system.The SA luminescence in ethanol is two orders stronger than that in water.The emission mechanism,the influences of forming process and surfactant on luminescent efficient is discussed.关键词：ZnS nanoparticle;self-activated luminescence(SA);vacancy;recombination114|101|4更新时间：2020-08-11
- 摘要：ZnS:Cu colloid optical properties,which vary with Cu+ doping concentration and aging process,were studied in thiourea and thiosulfurate systems.Exited at 325nm,ZnS:Cu colloid gives off a green band emission from 500 to 540nm,and the highest intensity appears in samples with doping concentration about 0.6%.The green emission band presents obvious red-shift as the Cu+ doping concentration increases,and it is also red-shift with the increasing reaction time.For the samples doped with 0.2% Cu+,a blue emission band at 450nm can also be observed besides the green one,and it will be quenched at higher doping concentration.The optical properties of thiourea and thiosulfurate system are quit similar,but the intensity of the latter is higher than that of the former.关键词：ZnS：Cu nanoparticle;thiourea;thiosulfurate;doping concentratio;aging process114|101|4更新时间：2020-08-11
- 摘要：In this paper,ZnS:TM(TM=Mn,Cu)colloid were synthesized by Sol-Gel method and their optical properties were studied by UV absorption spectra,PL and EL spectra.The size of particles is approximately 3～4nm deduced from absorption spectra.PL spectra show emission band of the corresponded doping center,which come from absorption of ZnS host.EL devices of ZnS:TM(TM=Mn,Cu)nanoparticle were fabricated by spin-coating method,the turn-on voltage and EL intensity with operating voltage were measured.A probable explanation was given for the PL and EL properties.关键词：ZnS：TM colloid;photoluminescence;electroluminescence;EL device97|55|1更新时间：2020-08-11
- 摘要：It is reported in this paper that CdS nanopatricle was synthesized in microemulsion,and the surface of CdS nanoparticle was decorated by depositing a layer of ZnS,then formed CdS/ZnS coated structrue nanoparticle.The size and the coated structure was characterized by absorption-spectra and TEM.The diameter of CdS core is 5nm.The total diameter of CdS/ZnS coated structure is 8～10nm.The blue shift of λthreshold and PL peak is caused by quantum size effect.The coating of ZnS can reduce the emission of surface traps of CdS nanoparticle and enhance the emission of band edge and lead it blue shift more.关键词：CdS;ZnS;nanoparticle;coated structure;microemulsion105|88|3更新时间：2020-08-11
- 摘要：Nanoscale Y2O3:Eu phosphors were prepared by thermal decomposition of the rare earth carboxylic acid complexes.The structure,size and morphology of particles were characterized by XRD and HRTEM.The cell parameters of nanoscale Y2O3:Eu are related with the doping concentration of Eu3+,annealing temperature and the ratio of rare earth ions(Re3+)and carboxylic acid.The size of Y2O3:Eu nanoparticle can be controlled by modifying the ratio of Re3+and ligand in the precursor.The excitation spectra shift towards the red when the content of Eu3+ is increased.The emission intensity is related with the composition of the complexes,the annealing temperature and the concentration of Eu3+.关键词：rare earth carboxylic acid complexe;precursor;Y2O3：Eu;nanoscale materials90|73|9更新时间：2020-08-11
- 摘要：In this paper,Sol-Gel method and microwave radiation method were used to synthesize the phosphors of silicate oxyapatites doped with Mn2+,or codoped with Mn2+ and Er3+.The high efficient,green color,subnanometer phosphors of Zn2SiO4:Mn2+,Er3+,with 150～350nm were obtained by means of these two methods.关键词：Sol-Gel;microwave radiation;Zn2SiO4：Mn2+;Er3+;photophosphor101|54|9更新时间：2020-08-11
- 摘要：In this paper,a new approach for preparing nanocrystalline Ge embedded in SiO2 by oxidizing hydrogenated amorphous SiGe films and hydrogenated amorphous Si/amorphous Ge multilayers.It was shown that,after oxidation,Si was bonded to oxygen to form SiO2 and nanocrystalline Ge was precipitated.Room temperature photoluminescence was observed by using Ar+ laser(488nm)at RT-and the luminescent peak is located at 2.2eV.The sample started from multilayers has a stronger luminescent intensity and narrower width compared with the sample started from SiGe films,which suggested the size distribution of nc-Ge could be controlled in this structures.关键词：nanocrystalline Ge;multilayer film;photoluminescence156|100|1更新时间：2020-08-11
- 摘要：The temperature dependence of photoluminescence(PL)peak in porous silicon is investigated.It was found that the PL peak shift is only dependent on measurement temperature.As increasing temperature,the peaks of PL from the specimens whose peak wavelengths are longer shift to higher energy,the peaks of PL from the specimens whose peak wavelengths are shorter shift to lower energy,and the peaks of PL from the specimens whose wavelengths are located to 740nm are independent of temperature.The PL origin is discussed in terms of a new model.关键词：porous silicon;photoluminescence;PL model118|87|3更新时间：2020-08-11
- 摘要：The viborational modes of RhB dye molecule adsorbed on the silver particles prepared on porous silicon electrodeposition were studied by Surface-enhanced Raman Scattering method.The experimental results showed the enhancement are associated with the electrodeposition time when the depositing condition remains invariable.关键词：surface-enhanced Raman scattering;porous silicon;dye molecul;electrodepisotion122|77|0更新时间：2020-08-11
- 摘要：In this paper we will report GaAlAs/GaAs gradient refraction index separate confinement quantum wells structures by MOCVD growth and its optical properties.The samlpe were characterized by high-resolution photoluminescence measurements.For 8nm single quantum well,the photo-luminescence spectra at 10K were measured which have a linewidth(FWHM)of 6.2nm and large intensity,indicating an abrupt GaAlAs/GaAs interface.The shift of X(e-hh)peak position versus the excitation level are also observed.The results of PL measurement show that sample quality has met the requirment of design and proven to be satisfactory.关键词：GaAlAs/GaAs;quantum well;photoluminescence162|78|0更新时间：2020-08-11
- 摘要：Optical interconnections are promising optical computing.It will take place of conventional electronic interconnections in many areas.Backplane optical interconnections between boards are studied at present.Beam spot shift mainly influences on quality of backplane optical interconnections between boards are presented.The causes are analyzed and first-order approximate formulas of relation between locations in the interconnections and slant degrees between two planes of light-guiding plate in the interconnections are deduced by using first-order approximation in this paper.According to laboratory deviations,different kind of deviation result and the total deviation result of interconnections are estimated.The method of overcoming beam spot shift in backplane optical interconnections is proposed.In the laboratory,high quality elements of backplane optical interconnections between boards are fabricated and it proves that the deduced approximate formulas in this paper are right.These will help to realize applications of backplane optical interconnections between boards.关键词：optical interconnection;location deviation;bragg grating100|76|0更新时间：2020-08-11
- 摘要：A new checking target method is proposed by utilizing up-conversion luminescence material for the first time,and we successfully provide the key device for the system of the dynamic checking target of laser TV.关键词：up-conversion;rare-earth fluoride;response time90|70|0更新时间：2020-08-11
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