最新刊期
卷 23 ， 期 1 ， 2002
- 摘要：Green,red,blue and white organic light emitting diodes(OLEDs)were investigated.Remarkable improvement in stability has been demonstrated in doped green and red devices.The QA doped green OLED achieved a long life time of 14 000 hours at initial luminance of 100cd/m2.The red OLED doped with red dye DCJTB showed high stability,the half decay time reached 7 500 hours at the initial luminance of 50cd/m2.Three blue device were constructed as following:ITO/CuPc/NPB/TPBi/Alq/MgAg(Cell BT);ITO/CuPc/NPB/DPVBi:Perylene/Alg/Alq/MgAg(Cell BD);ITO/CuPc/NPB/JBEM:Perylene/Alq/MgAg(Cell BJ).Here TPBi is a hole blocking meterial,DPVBi is a blue host,and JBEM is a new blue emitting mate-rial.On basis of the blue devices,putting the red dopant DCJTB into blue material TPBi,DPVBi,JBEM,or green host Alq,four white devices were produced.Experimental shows that the blue cell and white cell with blocking layer TPBi had much shorter life time than that of the conventional cell.It is obvious that the blocking layer is not favorable to the stability of the device,it may be attributed to the high barrier between the hole transporting and blocking layers.For the blue devices with JBEM as the host or DPVBi as the host,the former has better stability than the latter,showing the life time of 1 035 hours at initial luminance of 100cd/m2.For the white OLEDs,just like the blue devices,the cell with JBEM as the host had better performance than that with DPVBI as the host,and the device with blue dye and red dye DCJTB in the same layer showed high stability,the half decay time reached 2846 hours at initial luminance of 100cd/m2.A green,white panel display with 96×60 pixels and resolution of 2 lines/mm are constructed.The driving circuit was designed to eliminate the cross-talk between the pixels,a good image was realized.关键词：organic thin film electroluminescence;multi colors;high stability93|96|2更新时间：2020-08-11
- 摘要：The development of the organic quantum-well structure devices was introduced systemically.The conventional organic quantum-well structures were fabricated.The optical and electrical properties of the device were measured and the structures were scaled by the small-angle X-ray diffraction pattern.Based on the techniques,the organic quantum-well structure white light-emitting device was first fabricated and the performances were reported on the article.With the analysis of the possible effects on the performances of the organic quantum-well structure which induced by the fabrication technology,in order to decrease the diffusion effect at the interface of the quantum-well layer and barrier potential layer,the organic doping quantum-well structure was bring forward for the first time in the world.The structure consists of the alternating doping and undoping structure,in which the doping layer acts as quantum-well and the undoping layer as barrier potential layer.The performances of the device with the doping quantum-well structure were significantly enhanced and the results were analyzed.The optimum of the number of the quantum-well was also studied,and the result is two.Through suitable selection of the matrix and the dopants,the efficiency of the device would decrease slowly with the increase of the driven voltage.关键词：quantum-well structure;organic;electroluminescence111|94|2更新时间：2020-08-11
- 摘要：The synthesis,by co-ordination reaction,of a novel stable bis(8-hydroxyquinoline)zinc(Znq2)-containing metal complex polymer(copolymerization of Znq2 and 1,4-divinylene phenylene)is reported.The resulting polymer,which is characterized by EA and IR,shows strong orange-red emission(λem=571nm in solution).As determinded by TG analysis,the Znq2 containing polymer is thermally stable with a 5% weight-loss temperature higher than 439℃ under nitrogen.关键词：synthesis;metal-complex polymer;orange-red light emission91|86|5更新时间：2020-08-11
- 摘要：In this paper we focus on a new type of bis(1,3,4-oxadiazole)system and electron transportingmaterial-2,5-bis[2-(4-tert-buty/pheny/-1,3,4-oxadiazole-5-y1)]pyridine(PDPyDP).We have fabricated organic light-emitting diodes(OLED)using poly[2-methoxy-5-(2-ethy/hexoxy-1,4-pheny/ene)](MEH-PPV),ITO and aluminium as the light emitting layer,anode and cathode;with and without a thermallyevaporated electron transport layer of either PDPyDP or its vinylene analog 1,2-bis[2-(4-tert-buty/pheny)-1,3,4 oxadiazole-y1]benzene(PDPDP).PDPDP is the pare isomer of OXD-7,which is a widely used electron transporting material.Electroluminescence spectra for all devices indicate that light originates only from the MEH-PPV layer.The three bilayer structure devices possess almost identical current versus electric field data,suggesting a similar electrical transport process in each device.The lowest value of the turn-on electric field for EL has been observed for the OLED incorporating PDPyDP.At a current density of 50mA/cm2,the values of external quantum efficiency were 3×10-3% for the MEH-PPV single layer device,5×10-3% for the bilayer device using PDVDP,2×10-2% for the PDPDP-containing structure and 0.1% for the OLED incorporating PDPyDP.The reason of the above different EQE was analysed.It is worth noting that further improvement in the efficiency figures is possible by optimizing the device structure and material for the OLED incorporating PDPyDP.The calibrated quantum efficiency for ITO/PEDOT/MEH-PPV:Rubrene/Al device is 1.44%.关键词：organic light-emitting diodes;electron transporting material;oxadiazole111|96|1更新时间：2020-08-11
- 摘要：Bright and efficient organic electroluminescent(EL)devices have attracted considerable interest due to their potential application to flat panel display.To realized full color display applications,the three elemental colors of red,green,and blue emitters with sufficiently high luminous and color purity are necessary.After the last two decades of intensive research,a number of green and blue emitters with high luminance,high efficiency,saturated emission,and practical lifetimes have been developed.However,the corresponding development of the red emitters lags significantly behind that for the other two primary colors.Doping a red dye into a suitable host makes most high-performance of red EL devices.Nevertheless,the low efficiency at high doping concentration is due to the concentration quenching effect,which is common in fluorescence dopants.This problem can be avoided by using host red emitting materials,which can be used as emitting layer as well as hole or electron transport layer.In this paper,a novel red luminescent material N,N-bis-[4-[2-(4-dicyanomethylene-6-methyl-4H-pyran-2-yl)ethylene]phenyl]aniline(BDCM)with two electron-acceptor moieties(4-dicyanomethylene)pyran and an electron-donor moiety triphenylamine for application in organic EL devices was reported.The resultant compound has a sterically well-hindered structure and a high fluorescence yield.Its photoluminescence(PL)of this compound in solid film and EL have been studied.Based on its intense sterically hindered structure,the pure BDCM film prepared shows a bright red PL emission.The EL device with a structure of indium tin oxide(ITO)/copper phthalocyanine(CuPc)/1,3-diphenyl-5-(1-phenanthreneyl)-2-pyrazoline(DPPP)/BDCM/Mg:Ag shows a bright red emission and a brightness of 582cd/m2 at a driving voltage of 19V.And it can be found that CIE chromaticity coordinates of the device are nearly unchanged with increasing current density.As expected,the rigidity and non-planar structure of triphenylamine moiety offers BDCM a sterically well-hindered feature,and consequently an excellent pure red emission is obtained even for the pure BDCM.Further,the presence of two electron-acceptor moieties increase the electron affinity of BDCM,and as a result,grant the BDCM efficient electron injection and transport abilities.The combination of above advantages,as the result of incorporating triphenylamiline and two(4-dicyanomethylene)pyrane moieties into one molecule make BDCM serve as host red emitter possible.aniline(BDCM)with two electron-acceptor moieties(4-dicyanomethylene)pyran and an electron-donor moiety triphenylamine for application in organic EL devices was reported.The resultant compound has a sterically well-hindered structure and a high fluorescence yield.Its photoluminescence(PL)of this compound in solid film and EL have been studied.Based on its intense sterically hindered structure,the pure BDCM film prepared shows a bright red PL emission.The EL device with a structure of indium tin oxide(ITO)/copper phthalocyanine(CuPc)/1,3-diphenyl-5-(1-phenanthreneyl)-2-pyrazoline(DPPP)/BDCM/Mg:Ag shows a bright red emission and a brightness of 582cd/m2 at a driving voltage of 19V.And it can be found that CIE chromaticity coordinates of the device are nearly unchanged with increasing current density.As expected,the rigidity and non-planar structure of triphenylamine moiety offers BDCM a sterically well-hindered feature,and consequently an excellent pure red emission is obtained even for the pure BDCM.Further,the presence of two electron-acceptor moieties increase the electron affinity of BDCM,and as a result,grant the BDCM efficient electron injection and transport abilities.The combination of above advantages,as the result of incorporating triphenylamiline and two(4-dicyanomethylene)pyrane moieties into one molecule make BDCM serve as host red emitter possible.关键词：organic thin film;red light emission;electroluminescence;dicyanomethylene;triphenylamine90|110|0更新时间：2020-08-11
- 摘要：Electroluminescent devices based on organic semiconductors have gained a great deal of attention because of their high luminance,low drive voltage,and variety of emission colors.Different applications have different demands on the emitted light;sometimes colors are needed and in other cases it is necessary to have a bright white light source,especially for backlight applications in liquid crystal displays.Organic white light emitting diodes(LEDs)based on electroluminescent organic molecules have been reported using the microcavity technique,multilayer structures,multiple-quantum wells structures,or polymer LED based on polymer blends.However,most of the methods have the drawback that the chromaticity of emission coulor changes largely with the operating voltage,or the fabrication processes are more complex.We demonstrate efficient organic white light-emitting devices(LEDs),using N,N-diphenyl-N,N'-bis(1-naphthyl)-(1,1-biphenyl)-4,4'-diamine(NPB)as hole-transporting layer,1,6-bis(2-hydroxyphenyl)pyridine boron complex((dppy)BF)as emitting layer,tris-(8-hydroxyquinoline)aluminum(Alq)as electron-transporting and chromaticity-tuning layer.This type of device has a simpler structure than those mentioned above,thus the fabrication process is much simpler.The white light comes from exciplex emission at the solid-state interface between(dppy)BF and NPB and from the exciton emission of NPB and(dppy)BF layers respectively.The chromaticity of white emission can be tuned by adjusting the thickness of Alq layer.The white LEDs with the Alq thickness of 15nm exhibit a maximum luminescence of 2 000cd/m2 and efficiency of 0.58 lm/W,and the Commission Internationale De L'Eclairage(CIE)coordinates of resulting emission vary from(x=0.29,y=0.33)to(x=0.31,y=0.35)with increasing forward bias from 10V to 25V.The region is very close to equienergy white point(x=0.33,y=0.33).关键词：LEDs;organic electroluminescence;white light emission113|90|4更新时间：2020-08-11
- 摘要：A novel soluble bipolar conjugated Copolymer containing triphenylamine and 2,5-diphenyl-1,3,4-oxadiazole,Copolymer 5,has been synthesized.This Copolymer emits blue light in solution and film.The cyclic voltammograms(CV)shows this polymer has electrons and holes transporting ability.关键词：Copolymer;electrons and holes transporting;bipolar100|104|0更新时间：2020-08-11
- 摘要：Since the first successful fabrication of polymer light-emitting diodes(PLEDs),much effort has been devoted to the synthesis of new electroluminescent materials and the characterization of their photo-physical properties for their enormous potential application.Generally,conjugated polymers,such as MEH-PPV,dissolved in different solutions show various aggregation and morphology due to the solvent-polymer interactions.This is becacuse such difference is partly retained in polymer films,which are spin-coated from solutions.As a result,delocated and located electronic states of conjugated polymer,which determine the opto-electronic properties of polyme are affected strongly by the morphology and aggregation of polymer chains.Usually,close packing the conjugated polymer chains makes the distance of chains smaller and enhances the excimer formation,which reduces the PL quantum efficiency and makes PL spectrum a red-shift.However,little information has been attained about the influence of conformation structure of non-conjugated polymer on luminescent properties.But non-conjugated polymers are very important for the fabrication of PLEDs.It is very important to understand the nature of non-conjugated polymer chrompohores and their electronic and photonic properties.Here,a new type of poly(tris-8-hydroxyquinoline)derivative(Palq)spin casted from different solvents is reported to show obvious influence of film morphology on the absorption and luminescence spectra.When Palq film is spin coated from ethanol solution,their absorption and luminescent spectra show significantly red-shift in comparison with that of Palq film spin casted from chloroform solution.The PL peak of Palq film from ethanol solution locates at 510nm and its EL peak is at 540nm.While PL peak of Palq film from chloroform solution is at 488nm and its EL peak at 460nm.This is because that ethanol and chloroform show different polarity,the aggregation of Palq is different.While these different solutions are spin-coated into films,the aggregation of Palq solutions can be partly retained,which results in the difference of electronic structure of Palq films.As a result,the Palq films from different polar solvent represent different luminescent properties.Therefore,the choice of solvent is very important for luminescent characteristics of non-conjugated polymers in the fabrication of polymer light-emitting diodes.关键词：Palq;luminescent properties;solvent effect;aggregation83|94|1更新时间：2020-08-11
- 摘要：Since the first report of organic light emitting devices(OLEDs)in 1987 by C.W.Tang,much interest has been focused on the development of OLEDs for its potential application in full color flat panel display and optical communication.The balance of charge injection is of critical importance if highly efficient and low-voltage operating EL devices are to be realized.But in most OELDs,the injection of hole is much higher than the injection of electron.It was reported that the presence of a thin alkaline metal compound such as Li2O or LiF layer at an organic/Al interface significantly enhances electron injection.Among all these alkaline metal compounds,LiF gets the best effect.But the reason of this phenomenon is still unclear.In this paper,we studied the interaction between Alq3 and the alkaline metal compound,LiF.Alq3 samples with different LiF-doped concentrations on quartz substrate were made by means of co-evaporation.The ratios of LiF to Alq3 is 1:1,1:5,1:7 and 1:20.We also made the Alq3 sample without LiF.In all the samples,the thickness of Alq3 is the same but the concentration of LiF varies.The absorption spectra and photoluminescence spectra were measured.And we found that with the increase of the LiF concentration,the absorption edge,absorption peak and photoluminescence peak of the samples had shifted to the direction of shorter wavelength.It is believed that there are some electron traps in Alq3,and the LiF had filled some of the straps.So the absorption edge shifted to shorter wavelength with the increase of the LiF concentration.The shift of absorption peak and photoluminescence peak is believed to the due to the interaction between Alq3 and LiF.The use of LiF introduced ionic bond into the Alq3 film,so the distribution of the electronic clound of the quinoline group is changed,which caused the shift of the absorption peak and photoluminescence peak.关键词：Alq3;LiF-doped;interaction82|81|0更新时间：2020-08-11
- 摘要：After the first report of electroluminescence,EL,in poly(p-phenylenevinylene)(PPV)-based diodes,much effort has been devoted to the preparation of novel π-conjugated polymers in order to change the emission color and/or to increase the EL efficiency.At present the key research work for the ELDs still focus on the molecular design,synthesis and modification of luminescence materials.It is found that synthesis route,reaction conditions and raw materials used,all have strongly influence on the yield,solubility and luminescence of the product obtained.In this paper,four kinds of PPV derivatives with symmetrical and asymmetrical alkoxyl substitutes are prepared by dehydrochlorination process with p-methoxylphenol and p-diphenol as raw materials.The effects of synthesis route and reaction conditions are investigated in detailed.The molecular structure is characterized with IR,1H-NMR and UV-Vis spectroscopy.The thermal stability and thermo performance are obtained for TGA curves.The PL and EL characteristics are examined through fluorescent spectroscopy.The results show that PMOBOPV and PMOCOPV have excellent solubility and filming forming,which are better than PDBOPV and PDCOPV.Finally a single layer and two layer light-emitting devices were fabricated with PMOBOPV as light-emitting layer and Alq3 as electron transfer layer.The EL and PL are studied.It is indicated that for the single layer devices light-emitting voltage is 6V,the highest luminescence degree is 146cd/cm2;for two layer devices the luminescence voltage is 4V,the luminescence degree is 900cd/cm2 when applied voltage become 14V.关键词：poly(p-phenykenevinylene)derivative;electroluminescence device;synthesis95|64|2更新时间：2020-08-11
- 摘要：A new luminescent conjugated polymer containing triazole and triarylamine was synthesized by Suzuki coupling reaction.The polymer has well-defined structure and exhibit good thermal stability with the glass transition temperature in nitrogen at 101℃,which might be a merit for the long-life opration of light-emitting devices.The polymer is completely soluble in common solvents such as chloroform,tetrahydrofuran.Optical quality solid film is easily prepared form polymer by solution processing.The absorption spectra both the solution sample and film show three peaks,and the λmax are 370,290,and 245nm.The longer wavelength peak in the region of 370nm is attributed to the electron transition of along the conjuga-ted polymer main chain,the shorter wavelength peaks 290nm and 245nm are attributed to the triarylamine and triazole,respectively.The luminescent properties of the polymer in chloroform solution and in solid film were studied,the wavelengths of emission in film and solution at 458nm and 448nm.The resulting bipolar conjugated polymer emits a pure light,which is a promising candidate for polymer light emitting display.关键词：triazole;triarylamine;photoluminescence;synthesis100|62|0更新时间：2020-08-11
- 摘要：Near-infrared luminescence lanthanide complexes,which are found potential application in laser system and fibre communication,have recently draw more attention than ever.We suggest that near-infrared luminescent lanthanide complexes could also find application in rare earth ions fluorospectrometry and fluorescence immunoanalysis.The advantage layes in the low interference by coexist rare earth ions and can improve the reliability.In the present work,Ln-PAN(Ln=Yb3+,Nd3+ and Er3+,and PAN=1-(2-pyridylazo)-2-naphthol)complexes were synthesized and characterized by elemental analysis.Their near-infrared luminescence properties both in solid form and in solution were studied with a self-made luminescence determination system.It was found that near-infrared luminescence of Yb3+ and Er3+ complexes could be strongly sensitized by coordination of PAN,while that of Nd3+ complex could not be sensitized.An energy transfer mechanism was proposed to explain the near-infrared luminescence properties of Ln-PAN complexes.The difference between emission energy level of Yb3+,Nd3+ and Er3+ gives the different match effects with the triplet energy level of PAN.The luminescence intensity change dramatically with solvent,and ethanol solution gives the most intense emission.The fluorescence in ethanol solution is stronger than that in solid form,which was attributed to the concentration quenching effect.Unlike luminescent complexes of the commonly used lanthanide complexes of Tb3+,Eu3+,Sm3+ and Dy3+,which could only be excited with UV light,Ln-PAN(Ln=Yb3+,Nd3+ and Er3+)complexes could be excited with whole spectrum range of visible light,and this is a great advantage in choose light source for luminescence analysis.The near-infrared luminescence of a mixed Ln-PAN(Ln=Yb3+,Nd3+ and Er3+)solution also be determined independently,it shows there is no interference among the fluorescence of the three lanthanide ions.关键词：1-(2-pyridylazo)-2-naphthol;lanthanide;near-infrared luminescence83|89|3更新时间：2020-08-11
- 摘要：A perfect nonabsorbing microsphere with higher refractive index than the surrounding medium is a good optical microcavity.Inside such a sphere,which has a diameter of a few microns,there are a discrete number of resonant optical modes.The spontaneous emission cross-sections at the microcavity resonance photon energies are larger than the bulk spontaneous emission cross-sections because of the modified photon density of states of the microcavity.In the conventional study on microsphere,the luminescent molecules are inside the microspheres.In this paper,we report the fluorescent resonances of a dye solution outside a micrometer-sized,nonluminescent,spherical particle.Oxazine 1 was dissolved in distilled water,and its concentration was adjusted to 10-3mol/l.TiBa glass microspheres(refractive index～1.88,diameter=20～50μm)were dispersed in the aqueous solution of oxazine 1.One drop of the solution was put on a glass plate,and placed on a microscope stage at room temperature.The experimental apparatus is micro-Raman spectrometer(RENISHAW System 2000).The laser beam at wavelength of 633nm was introduced into an optical microscope and focused into a～5μm spot by an objective lens(20x,numerical aperture 0.4).The laser beam was irradiated on the edge of the microsphere,so that the oxazine 1 aqueous solution just outside of the microsphere was excited.Emission from the microsphere was collected by the same objective lens,and the spectra were observed by the spectrometer(with CCD).关键词：fluorescent spectrum;glass microsphere;morphology dependent-resonances;laser dyes94|69|0更新时间：2020-08-11
- 摘要：In this paper,the tetraethoxysilane(TEOS)precursor is hydrolyzed with ethanol as co-solvent under various concentrations of hydrochloric acid catalyzer to prepare the alkoxysilane pre-polymer solutions containing the luminescent Ru(dpp)32+ complex through sol-gel process.A series of oxygen-sensing films were fabricated by spin coating of such pre-polymer solutions onto glass slides followed by aging and drying of resultant gels.The effects of acid catalyzer concentration on the micro-structures of sol-gel matrices and the micro-environments of luminescent molecules are revealed by the luminescent quenching behaviors of Ru(dpp)32+ complex within such sol-gel matrices under various oxygen concentrations.It is shown that the maximum emission peak of Ru(dpp)32+ in sol-gel matrices is almost independent on the acid catalyzer concentration,suggesting that very dinky change of chemical micro-circumstance around Ru(dpp)32+ complex can induced.Compared in ethanol solution,the emission peak of Ru(dpp)32+ in solid state exhibits a red shift for about 14nm,and the red shift for Ru(dpp)32+ in sol-gel matrix is only 4nm,suggesting that such matrices are excellent dispersoid for Ru(dpp)32+ complex.The quenching responses of all prepared oxygen sensors generally exhibit excellent stability,reproducibility and high signal-to-noise ratio.The sensor performances such as quenching response Q,Stern-Volmer coefficient KSV and response times(both quenching time tQ and resuming time tR)are improved with decreasing acid catalyzer concentrations.Since the acid catalyzer concentration has almost no effect on the chemical micro-circumstance around Ru(dpp)32+ complex,it seems that these improvements of sensor performance are mainly due to faster diffusion rate of oxygen in sol-gel matrices and higher collisional probability of oxygen with Ru(dpp)32+.Two facts may contribute to such improvements:firstly,the sol-gel matrices with more open and porous structures are favored when lower concentration of acid catalyzer is used;secondly,the polar Si-OH groups that have strong interaction with oxygen may be partially replaced by negative SiO- that cannot absorb oxygen under lower concentration of acid catalyzer.关键词：sol-gel;luminescence;oxygen sensing93|88|1更新时间：2020-08-11
- 摘要：A piece of novel optical storage material-PPV/SiO2 sol-gel material has been produced in the following steps:(1)PPV precursor has been synthesized by Wessling method;(2)PPV/SiO2 sol-gel complex material has been prepared by mixing silicon sol and PPV precursor and then through the process of gelation,vaporization and heating;and(3)the material has been doped with the polymer(methyl methacrylate)to improve its characteristics.STM,UV and FT-IR have been used to analyze the physical properties of the composite material.The STM photography of SiO2 sol-gel shows porous structure with size of about 100nm.The UV and FT-IR absorption spectra show that PPV has been produced in the complex system after the heating process.In the two-beam coupling experiment,asymmetric energy transfer has been observed.While the material was irradiated by two laser beams of equal intensity,one beam increased and the other decreased at the same time and then got to saturation.A photorefraction-like mode has been used to explain the phenomena.The dependence of absorption and diffraction efficiency on PPV concentration has also been investigated.The results indicate that both of them increase with concentration with PPV.The absorption and diffraction efficiency are also influenced by doping or un-doping PMMA.关键词：PPV;two-beam coupling;photorefraction;absorbance78|58|3更新时间：2020-08-11
- 摘要：The properties of the electron-ripplon system on the surface of liquid helium film influence the properties of liquid helium very markedly.The problem of a two-dimensional electron on the surface of a liquid helium film was formulated by Jackson and Platzaman as a surface polaron problem.The properties of eleron-ripplon system on the surface of liquide helium film have been of considerable interest.The surface polaron in the eletron-ripplon system is investigated by Tokuda within the modified variational scheme of the Lee-Low-Pines theory which is valid for the whole range of the eletron-ripplon coupling.Jackson and Peeters have applied and extension of the Feynman path-integral formalism to the problem of noninteracting polaronic electron on the surface of a liquid helium film in a perpendicularly applied magnetization field.The ground state energy,the Feynman-model mass,the magnetization,and susceptibility of the system are calculated.The Landau-pekar variational theory for investigating the strong-coupling system of electron-phonon in crystals is employed by Jin Pei-wan et al.to study the system of an electron strongly coupled to ripplons on the outer surface of the liquid-helium film.Analytical expressions of the ground state energy,the effective mass,and the average number of virtual ripplons around the electron are obtained.Huybrechts proposed a linear combination operator method,by which a strong-coupling polaron was investigated.On the basis of Huybrechts' work,Tokuca added another variational parameter to the momentum operator and also evaluated the ground-state energy and effective mass of the bulk polaron.In fact,so far research on the electron-ripplon system has been restricted to approximation and calculation where the interaction between ripplons of different wave vectors in the recoil process in neglected.The properties of the surface magnetopolaron and the surface polaron,considering the corresponding interaction,have been discussed by the present authors.The effect of the interaction between ripplons of different wave vectors in he recoil process on the effective mass of the electron-ripplon system are studied by using linear combination operator and pertur-bation method in this paper.关键词：films of liquid helium;ripplon;effective mass77|49|0更新时间：2020-08-11
- 摘要：In recent years,oxidative damaged DNA by hydroxyl radical(·OH)has been received much attention.But the reports on oxidative damaged RNA by ·OH were quite limited.In fact,RNA,being the same as DNA,is also one of big two components for nucleic acid.It also has many important functions.Therefore,RNA attacked by ·OH leads to serious consequence,which bring about decline of the cell activity even death of the cell.Thus a chemiluminescence system for generating and detecting oxidative damaged RNA by ·OH was made,which initiated with Vit.C/CuSO4/Phen/H2O2/RNA,so as to strengthen the study on oxidative damaged RNA by ·OH.Through the investigation on detecting conditions of the system,optimal scheme of the system was obtained:concentration of Vit.C,CuSO,Phen,H2O2 and RNA were 350μmol/L,55μmol/L,350μmol/L,0.2mol/L and 20μg/mL,respectively.The pH of the system was 5.5.The final volume was 1mL.Using the system,we detected the effects that quercetin,caffeic acid,baicalin and rutin resisted oxidative damaged RNA by ·OH and found that the four antioxidants could effectively inhibited oxidative damaged RNA by ·OH.These facts also proved feasibility and practicality of the system.Molecular mechanism for oxidative damaged RNA by ·OH was analyzed by the system and special antioxidants.The results indicated that sulfocarbamide which was a ·OH scavenger nearly inhibited whole chemiluminescence.The reason for the phenomenon was that RNA oxidative damage was not initiated only because sulfocarbamide scavenged ·OH,an initiator;catalase also inhibited whole chemiluminescence,revealing that ·OH couldn't be generated due to H2O2 removed by catalase.SOD,a O2· scavenger,could only inhibit a small part of chemiluminescence,whereas NaN3 or benzene carboxylic acid,a 1O2 scavenger,could inhibit most of chemiluminescence.These results suggested that ·OH is an initator;but O2· is a minor factor,1O2 is a major factor for the RNA oxidative damage.关键词：hydroxyl radical;RNA;oxidative damage;chemiluminescence102|72|0更新时间：2020-08-11
- 摘要：We realized the erasable holographic storage in visible region for the thin layers of PMMA matrices doped with N-salicylideneaniline material.An argon laser beam of 488.0nm and a He-Ne laser beam of 632.8nm were used for writing and reading,respectively.With the reading light of 0.5mW,we studied the relationship between the intensities of the two writing beams and the intensity of the diffraction signal.The results and explanations were as following.For a given intensity of the writing beams,the intensity of the diffraction signal for the writing process increased at first,then decreased with the increase of time.A possible explanation is that pressure-driven mass transport induced from photo-isomerization which causes a change on the surface to form a surface-relief grating.However the surface-relief grating partly counteracts the phase-grating resulting from the two gatings with phase difference of π.We also found that the intensity of the diffraction signal depends on the intensities of the two writing beams.Higher intensity of the diffraction signal was observed with higher power of the writing beams.It is believed that the writing beams with higher intenisties cycle more SA molecules through a keto-enol-keto cycles.So the phase grating formed by the oriented molecules through photo-isomerization is stronger than that formed with the writing beams with lower intensities.Because the intensities of the writing beams have a more important influence on the phase grating than on the surface-relief grating.So the resultant grating formed by the counteraction of the surface-relief grating and the phase grating strengthened,we could observe the diffraction signal with higher intensity.To confirm the surface-relief grating,under same writing condition,we carried out the erasing process and investigated the relationship between the intensity of the erasing light and the erasing rate.For a given power of erasing light,we also observed that the intensity of the diffraction signal increased firstly,then decreased with the increase of time.It is considered that one erasing beam would homogeneously distributed on the recording spot,without the gradient of the light intensity.So there would no isomerization pressure and the mass transport in the recording region would stop,which made the surface-relief grating kept and restrained.At the same time,because there exists a dynamic equilibrium of photo-isomerization,the phase grating would reach the equilibrium state firstly,then would grow weak because of the change of the refractive indexes(Δn)between the regional bright and dark region become small with the erasing light.So the resultant grating formed by the two grating would strengthen at first,then would weak.So we could observed the phenomenon.Higher erasing rate was observed with higher power of the erasing beams,which can be contributed to the more quick decrease of Δn with higher intensity of the erasing light.In summary,we believe that the mechanism of an isomerization-driven pressure led to the formation of the surface-relief grating and these phenomena are due to the change of the resultant grating formed through the counteraction between the surface-relief grating and the phase grating.关键词：N-salicylideneaniline;optical storage;holographic grating84|115|0更新时间：2020-08-11
- 摘要：With different properties from their bulk materials and potential applications in various fields,semiconductor quantum dots have been researched for several decades.The studying follows three directions:preparing quantum dots of new materials,finding novel preparation method and building up complex heterostructures,such as core-shell structures,quantum dot quantum well structures and so on.Owing to the quantum confinement effect,the rate of radiative transition and the effectiveness of the excitation transfer in quantum dots may be bigger than those in bulk materials,but surface states usually act as luminescence killers.So researching and controlling the surface of quantum dots are important.Because of the good passivation of the shell,some core-shell quantum dots have displayed a quantum yield of 50%.The electronic properties of quantum dot quantum well may be controlled by tuning the thickness and the energetic structures of various layers.The luminescence with high efficiency may be obtained.ZnS has a cubic structure of blende-type very close to that of CdS and a large band gap compared to that of CdS.These are the basic conditions to form a quantum dot quantum well with ZnS and CdS.In this paper,ZnS/CdS/ZnS quantum dot quantum well was prepared by inverted micelles method and was characterized.Dioctylsulfosuccinate sodium salt(AOT)was used as surfactant.The size of the quantum dot quantum well was controlled by the water-to-surfactant mole ratio.The size distribution was narrow and the diameter of the quantum dot quantum well was about 4.5nm,which was consistent with the theoretical calculation.The optical properties were compared with those of core-shell ZnS/CdS quantum dot.Both emissions of the quantum dot quantum well and the core-shell structure were peaked at 515nm which can be attributed to the donor-acceptor recombination in CdS.The luminescence of quantum dot quantum well was stronger than that of the core-shell structure.This can be explained that the ZnS shell of the quantum dot quantum well increased the distance from CdS to surface states,reducing the nonradiative recombination rates.The luminescence decay was measured and the decay curves were fitted by a hyperbolic function.The results indicated that the ZnS shell reduced the relative contribution of the fast process to the overall emission.The luminescence lifetime of quantum dot quantum well was longer than that of the core-shell structure.关键词：quantum dot quantum well;ZnS;CdS;luminescence113|99|1更新时间：2020-08-11
- 摘要：The up-conversion luminescence properties of Er-Yb codoped new fluoride ceramic and glass were studied.Intense violet,green and red up-conversion emissions were observed with 978nm LD as an excitation source.In comparison with the up-conversion spectrum of Yb-Er codoped systems reported previously,the violet and red emissions in our sample were enhanced greatly.The up-conversion emission spectra of ZAPL:10% Yb3+,5% Er3+ glass and ceramic excited by 978nm LD laser were measured.The up-conversion emission spectra under different excitation densities for oxide-fluoride,glass(10% Yb,3% Er)and fluoride glass and ceramic(10% Yb,5% Er)were also presented in this paper.In order to clarify the enhancement mechanism,the excitation spectra with different wavelength were measured.The experimental results indicate that two cross-relaxation processes between Yb and Er:4G11/2→4F9/2(Er3+)and 2F7/2→2F5/2(Yb3+),2H9/2→4F9/2(Er3+)and 2F7/2→2F5/2(Yb3+)make the red up-conversion emissions enhanced greatly.The enhancement of violet emission is attributed to the low energy and narrow band phonon in our sample.We explain up-conversion fluorescence properties of Er-Yb co-doped oxide-fluoride vitro-ceramic excited by 978nm LD at the end.99|74|1更新时间：2020-08-11
- 摘要：The high power linear graded-index separate-confine-heterostructure signle-quantum-well GaAs/AlGaAs lasers have been grown and fabricated by MOVPE method.The maximum continue wave output optical power is up to 500mW for the lasers with 300μm wide stripe and 600μm cavity length.Threshold current is 137mA and emitting wavelength is 820.3nm at room temperature for continue wave operation.The measured vertical and parallel divergance angle are 4.5°and 38.2°,respectively.That is the advantages of graded-index separate-confine-heterostructure,thus it can get a higher efficiency in the application of pump solid lasers and fiber output.关键词：GRIN;SCH;SQW;lasers80|96|0更新时间：2020-08-11
- 摘要：Among the established techniques for measuring fluorescence decay rate,time-correlated single-photon counting(TCSPC)provides unusually high sensitivity,and is,widely used.Sample's decay curves measured by the TCSPC system contain the system's respond function.In order to get the real decay curve of the sample,we have to do the deconvolution.For that,we need a method to do the nonlinear fitting.By now those established nonlinear fitting method have the problem that resolution is sense to the given initial value,and need too much time to do the calculation.To overcome those disadvantages,we build up a new method to do the fitting.The method is based on the practical pace-accelerated means.It has nice precision and good repetition.For a common value,it can easily work out a fairly good resolution.Using this program,we analyzed some sample's decay curve.The result shows that the new method is useful for the fitting to the fluorescence decay curves.关键词：fluorescence decay;deconvolution;least-square solution150|105|4更新时间：2020-08-11
- 摘要：Epoxy resin is one of the essential materials of LED,its performance affects directly on the reliability and output effect of the products.So,in the process of manufacturing LED,the epoxy resin should be selected according to the situations,make sure the product are satisfied customers' requirements.1.The influence of epoxy resin upon the reliability of the products Use №.02,12,14(with other same material e.g.chips)to package φ3 transparent type LEDs.In half of them is used in the second bond position to fix.Carry the soldering heat-resistant trial and PCB trial on the products(store in high temperature in the condition of external force).It is proved that №.14 epoxy resin is the best choice for improving products reliability.2.The influence of epoxy resin upon the light output effect of the products Use №.02,12,14(with other same material e.g.chips)to package 5 transparent type infrared LED(each 20 pcs).Test the light power of some samples.It showed that considering the light output efficiency,we should select №.12 epoxy resin.Test the samples connecting power supply in low temperature to evaluate the output stability of the products.It is proved that those products with the worse output have the little light output diminution as time goes by.Carry on the same light output and light diminution comparison tests on visible light LEDs,we have the same conclusion.So,it can be proved that the conclusion mentioned above is correct and common.3.The light selecting performance of epoxy resin According to the spectra of three kinds of photodiode made from different epoxy resins in the tests,we found light with wavelength in the range of 700～1 000nm is easy to pass through for 18C epoxy resin and 10B epoxy resin.Obviously,this material is not suitable for manufacturing the infrared opto-devices with high requirements on light selecting performance.While the 02B epoxy resin is only sensitive to infrared light with wavelength over 800nm.Using this kind of epoxy resin as packing material,it can make the products have excellent anti-jamming ability.Use special light source to shine directly on the surface of the devices,and send a same infrared signal in the same distance,18C and 10B epoxy resin have very slow response even have no response.While 02B products keep much sensitive,very like that with infrared light shining directly.It is consistent with to the result from the spectrum of tests.To conclude,the performance of epoxy resin have important effects on the reliability,the light output of the LED and the anti-jamming ability of the opto-devices.And we should select suitable epoxy resin according to the situations.关键词：epoxy resin;reliabilty;light output efficiency;light selecting performance93|120|0更新时间：2020-08-11
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