最新刊期
卷 21 ， 期 4 ， 2000
- 关键词：luminescence;multi-colour display;stability145|69|0更新时间：2020-08-11
- 摘要：Crystal structure and Ce3+,Tb3+-doped luminescence of NaZnLa(PO4)2 prepared through conventional high-temperature solid state reaction were investigated. The cell parameters calculated from the powder X-ray diffraction pattern of NaZnLa(PO4)2 are a=0.6823nm, b=0.7045nm, c=0.6497nm, β=103.9°, V=0.303nm3.Its cell constants and unit-cell volume are comparable to those of monoclinic LaPO4 with monazite-type. The fact that NaZnLa(PO4)2 is isostructure with LaPO4 is also identified by IR. The IR spectrum of NaZnLa0.78Ce0.1Tb0.12(PO4)2 (see table 2) are similar to that of LaPO4 and the local site symmetry of PO4 also belongs to Cs. The luminescence of Ce3+,Tb3+-doped NaZnLa(PO4)2 showed that the Ce3+ ion has a strong f-d absorption band around 250～320nm and its 5d →7Fj (j=7/2,5/2) emission band overlaps with Tb3+ 4f-4f excitation spectrum. Thus green emission of Tb3+ can be efficiently sensitized by Ce3+. The optimum concentrations of Ce3+ and Tb3+ in NaZnLa1-x-yCexTby(PO4)2 were x=0.2～0.4 and y=0.08～0.16,respectively. The green emission of Tb3+ can also be enhanced by co doping with appropriate amount of BO33- (～0.12 mole/formula), Al3+ (～0.04 mole/formula), and Dy3+ (～0.001 mole/formula). Comparing with LaPO4, the synthesis temperature of NaZnLa1-x-y-z-wCexTbyDyzAlw(PO4)2-v (BO3)v is lower and the consumption of rare earth used for synthesis is less because part of rare earth is substituted by Na and Zn.关键词：NaZnLa(PO4)2;cerium;terbium;luminescence81|94|2更新时间：2020-08-11
- 摘要：The ZnCdSe/ZnSe asymmetric double quantum wells(ADQW)samples studied were grown on(100)Si-doped GaAs substrates by low pressure(LP)MOCVD. The sample structure consists of a 1μm ZnSe buffer layer followed by ten periodes of Zn0.72Cd0.28Se/ZnSe ADQW and then a 60nm ZnSe cap layer. Each period of ZnCdSe/ZnSe ADQW includes one narrow ZnCdSe quantum well, one thin ZnSe barrier and one wide ZnCdSe quantum well. Each period of the ADQW was separated by a 40nm ZnSe barrier. Exciton tunneling has been studied in the ZnCdSe/ZnSe ADQW. There are two emission peaks of the time-resolved spectra of the ADQW corresponding to n=1 heavy hole recombination from the wide well (WW) and narrow well (NW), respectively. It is obvious that the n=1 heavy hole excitonic emission from the WW dominates the spectra, and the n=1 heavy hole excitonic emission from the NW decreases and disappears gradually with increasing the delay time. Considering the exciton tunneling in the ADQW, this phenomenon can be explained. Under stronger excitation, the tunneling of free electron and free hole are also observed in the ADQW. Due to different tunneling time of free electron and free hole, space charge effect was observed in the ADQW, which leaded to the foundation of the internal electric field. The excitation intensity dependence of the luminescence intensity in the WW and NW as shown in fig.5 can be explained by foundation of the internal electric field. The spontaneous and stimulated emission have been studied in the ZnCdSe/ZnSe ADQW. For spontaneous emission of the ADQW, the exciton recombination both in the NW and WW is influenced by two factors, the exciton tunneling and the thermal dissociation processes. For the NW, the two factors have the same influence on the emission intensity, but for the WW, the influence on the emission intensity of two factors are contrary. The change of the emission intensity in the WW is determined by the stronger one. For stimulated emission of the ADQW, owing to the difference of the energy levels between the WW and the NW, the carriers tunnel from the NW to the WW, which can influence the emission effectively.The carrier tunneling is conductive to lasing from the WW.关键词：ZnCdSe/ZnSe ADQW;exciton tunneling;stimulated emission94|94|1更新时间：2020-08-11
- 摘要：Low-temperature time-resolved luminescence experiments have been performed on a semiconductor planar microcavity which contains two In0.13Ga0.87As/GaAs quantum-wells(QWs)embedded in a two-third-wave cavity.The excition-photon mixing was observed in the structure.The spontaneous emission dynamics of the each of the two components were studied as a function of the excition-cavity detuning under nonresonant optical excitation.In the strong-coupling regime,the decay times of the low and the upper branch cavity polaritons are almost independent of the cavity detuning.Considering the special structure of a planar microcavity,the polariton states with k∥ in the strong-coupling region hold only a small fraction of the radiative states(roughly 10%).Most of the rediative states are within the leaky modes of the distributed Bragg reflectors.The photoluminescence decay times of the upper and low branch polaritons are uniquely determined by the radiative states within the leaky modes.Therefore,the decay time is independent of detuning.However,we observed that the rise times of the low and the upper polaritons are obviously different.The rise time of the low branch is independent of the detuning and that of the upper branch is a marked dependence on the detuning.Due to the bottleneck effect and the faster radiative rate of the low branch at k∥=0,the rise time of the PL of the low branch at k∥=0 is only determined by the population buildup time at the bottom of the excitonlike branch.Hence it is detuning independent.With respect to the rise time of the upper branch,the population of the upper branch mainly comes from the excitons of the low branch with the same energy.In particular,the energy of the upper branch polaritons with k∥=0 for larger positive detunings is much higher than that of the bottleneck region and cooling excitions can easily reach these states well before reaching the bottom of the excitonlike branch.Consequently,the PL rise time of the upper branch becomes faster.On the opposite side of the detunings,the upper branch becomes excitonlike,the PL rise time approches the value of the low branch.Thus,the rise time of the upper branch depends significantly on the detuning.关键词：semiconductor planar microcavity;InGaAs quantum well;time-resolved PL spectra91|85|0更新时间：2020-08-11
- 摘要：Recently,organic electroluminescent devices have demonstrated a remarkable progress.The lifetime has been over 10000h.Even so,how to improve efficiency has also attracted much interest.In this paper,by comparing to low dimension structure characteristic of inorganic semiconductor,we indicate,for some organic materials system,low dimension structure can also improve the property of device.98|106|0更新时间：2020-08-11
- 摘要：Green, red, blue and white organic light emitting diodes (OLED) were investigated. Remarkable improvement in stability has been demonstrated in doped green and red devices. For OLED with the structure ITO/CuPc/NPB/Alq:dopant/MgAg,copper phthalocyanine (CuPc) was used as a buffer layer, N,N’-bis-(1-naphthyl)-N,N’-diphenyl-1,1’-biphenyl-4,4’-diamine(NPB) as the hole transporting layer, tris(8-quinolinolato) aluminum complex (Alq) as ETL, indium tin oxide (ITO) and MgAg as the anode and cathode, respectively, coumarin545(C545) and quinacridone (QA) were used as the dopants for green device, while DCJTB was for the red device. For green OLED, the devices with two kinds of dopant were compared. It is shown that C545 doped device gives more higher luminance, however, its half life is shorter than that of QA doped cell. The QA doped green OLED achieved the long life of 14000h at initial luminance of 100cd/m2. The red OLED doped with red dye DCJTB showed high stability, the half decay time reached 7500h at the initial luminance 50cd/m2 and the change of driving voltage was 0.6mV/hour in the degradation process. Two kinds of blue OLEDs with the structure ITO/CuPc/NPB/TPBi/Alq/MgAg and ITO/CuPc/NPB/DPVBi:perylene/Alq/MgAg were studied. The former was a device with blocking layer, here TPBi acts as a hole blocking layer due to the high barrier in the interface between it and NPB, the latter was conventional one. Luminance degradations of the two devices were compared.It showed that the blue cell with blocking layer had much shorter life time than that of the conventional cell.The latter showed the half decay time of 450h at the initial luminance 50cd/m2. Based on the above blue OLEDs, two white OLEDs were constructed. The structures were ITO/CuPc/NPB/TPBi:Rublene/Alq/MgAg and ITO/CuPc/NPB/DPVBi:perylene/Alq:DCJTB/MgAg.The same results about the luminance degradation have been obtained. The device without blocking layer had the half decay time of 300h at the initial luminance 50cd/m2. The white OLED with blocking layer had a short durability. It is concluded 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.关键词：organic emitting diode;multi colors;high stability112|78|2更新时间：2020-08-11
- 摘要：This paper summarized the work in nanometric scale luminescent materials Y2SiO5:Eu and Ln2O3:Eu(Ln=Y,Gd)prepared by sol gel process and combustion synthesis respectively,including the excitation spectra,emission spectra,lifetime,concentration quenching and the dependence of them on the grain size.It is found that quenching concentration in nanocrystalline Y2SiO5:Eu and Ln2O3:Eu is higher than that in normal materials.This is ascribed to the influence of a confinement effect on resonant energy transfer in nanosized particles.These properties show that nanocrystalline luminescent materials has important potential applications. Site selectively excited luminescence and energy transfer of X1-Y2SiO5:Eu at nanometric scale were mentioned too.There were four different luminescent centers in nanosized X1-Y2SiO5:Eu.Two of them belong to Eu3+ embedded in nanosized X1-Y2SiO5:Eu,the other two attributed to trace of Y2O3:Eu and to a particular site on the surface.A pronounced excitation energy transfer between the two sites of nanosized X1-Y2SiO5:Eu was observed and discussed.关键词：nanometric materials;luminescence of rare earth;Y2SiO5：Eu;Y2O3：Eu98|97|11更新时间：2020-08-11
- 摘要：The semiconductor solid phase epitaxial model of continuous laser-annealing is used to simulate the laser-annealing process of monocrystalline silicon at the continuous Nd:YAG laser.Specially,at lower power density of laser,quasi-static model is used to simulate the radial heat dissipation from irradiated region to nonirradiated regions.A partial linear method is used to deal with non-homogeneous nonlinear equation of heat conduction.Then a hidden-form differential equation is gotten.Using the program of chasing method to solve the equation,the distribution of temperature(T(z,t))at time and space can be worked out accurately at the condition of adiathermic boundary.Furthermore,the thickness of recrystallization of laser-annealing is gotten.At laser wave λ=1.06μm,the power density of laser I0=700W/cm2 and the preheated temperature T0=523K,the result is that the temperature of surface reaches to about 1290K and the thickness of recrystallization is about 0.5μm after 0.7sec.关键词：monocrystalline silicon;laser-annealing;solid phase epitaxy;quasi-static model;hidden-form differential equation136|125|0更新时间：2020-08-11
- 摘要：The processing and characteristics of InGaN/AlGaN double heterojunction (DH) structure and of GaN epilayer grown on the α-Al2O3 substrate by means of metalorganic chemical vapor deposition (MOCVD) technique are reviewed. The important effect of the MOCVD growth condition (temperature, gas source flow etc.) of the GaN buffer layer on the surface morphology, crystallinity and opto electronic properties is discussed from the point of view of the surface dynamics. The analysis indicates that the growth rate of GaN film is dependent chiefly on the furnace temperature, the molar flow rate of the gas sources. As increasing the temperature, the PL peak shifts to longer wavelength. The growth temperature of the GaN buffer layer must be controlled at 550℃. The high ratio of Ⅴ/Ⅲ gas source flows can restrain the radiant intensity about 550 nm in the GaN photoluminescence spectrum. To obtain a good epilayer film with high radiation rate the Cp2Mg source is used as the Mg acceptors doping in p-AlGaN and p-GaN compound semiconductor. It is noticed that,the epitaxial temperature and time, Mg doping dose should be optimally controlled, furthermore, the sample is annealed rapidly at 800℃ under the N2 gas flow. In fact, above mentioned efforts have been made importantly on the lattice microstructure improvement and the increase of luminous intensity for the InGaN/AlGaN DH LED.关键词：InGaN/AlGaN;processing condition;LED;growth dynamic101|136|0更新时间：2020-08-11
- 摘要：Electroplating and direct brushing technique were used to deposit commercial HTHP diamond powder on W needles and Si substrates to form cold cathodes.These cold cathodes combined with phosphor anodes constructed testing vacuum diodes.By measuring current-voltage characteristics and observing light emission of these diodes,electron emission feature of these diamond powder cold cathodes were investigated.Experiments show that,these cold cathodes have good electron emission ability,the minimum threshold field is 3.25V/μm.Thermal-electric positive feed back and conductivity modulation effects were proposed to interpret the phenomenon of random distribution of electron emission sites.关键词：diamond powder;field emission82|96|1更新时间：2020-08-11
- 摘要：Ⅱ-Ⅵ compound semiconductor materials, in particular ZnCdSe-ZnSe superlattices have been extensively studied in the past several years due to their potential applications in blue and blue-green laser diode (LD). ZnSe-based LD generally use a single quantum well or multiple quantum wells structure as an active layer where light is emitted. In this paper the stimulated emission is studied in a special kind of superlattice structure-ZnCdSe-ZnSe compound superlattices,in order to try a new structure for the LD’s active layer. The sample used here was grown by a low pressure MOCVD on GaAs(100) substrate. The ZnCdSe-ZnSe compound superlattices have two groups of superlattices SL1 and SL2 with different Cd compositions which separated by a 50nm ZnSe isolating layer. The double superlattices are embedded in an 12μm ZnSe buffer layer and an 150nm ZnSe cap layer. The superlattice SL1 with Cd composition 10% near the buffer layer have 20 periods, well width 5nm and barrier width 6nm, and the superlattice SL2 with Cd composition 7% have 20 periods, well width 3nm, and barrier width 6nm. Photo luminescence and photopumped stimulated emission spectra were excited by the 337.1nm line of a UV-24 N2 laser working at 10Hz, and the signals were measured at 77K using a SPEX1404 double grating monochromator with a RCA-C31034 cooled photomultiplier. The samples used in the stimulated emission measurement were cleaved in approximately 2mm wide resonators and the Fabry-Perot cavities were formed by the natural facets of the sample bars. Fig.1 and Fig.2 show the emission spectra from the surface emission and the edge emission of the samples, respectively. There are four bands a, SL1,SL2 and L in Fig.1 and Fig2. The band L increased rapidly with increasing the excitation intensity. We can attribute the bands a,SL1 and SL2 to spontaneous emission from ZnSe barrier and superlattices, respectively. We can also attribute the band L to stimulated emission from superlattice SL1.Due to the carrier transfer between the double superlattices, the stimulated emission mainly appeared in the superlattice with wide well. The gain spectrum was shown in Fig.3. According to the dependence of the stimulated emission intensity from the cleaved edge on the strip length of excitation, the magnitude of the optical gain is found to be about 72cm-1.关键词：MOCVD;ZnCdSe-ZnSe compound superlattices;stimulated emiss93|106|0更新时间：2020-08-11
- 摘要：A new method based on the series equivalent circuit of a diode was introduced to characterize the semiconductor diodes, through which the electrical characteristics such as the series resistance, the junction capacitance at forward bias, and the interfacial layer resistance and capacitance can be evaluated. By using this method, the p-n junction blue light emitting diodes (LEDs) fabricated by the wide-gap GaN semiconductor material were measured and analyzed, and the negative capacitance effect (NCE) of the GaN p-n junction diodes was observed and reported firstly. The negative capacitance appears more noticeable with the lower frequencies and the larger forward bias. It is found that the negative capacitance effect is constantly accompanied by the diode lighting. This phenomenon is explained by considering the electron-hole recombination lighting under high injection with large forward bias. The research on negative capacitance will be valuable for the improvement of the design, fabrication and characterization of the GaN semiconductor LEDs.关键词：GaN;LED;negative capacitance105|88|1更新时间：2020-08-11
- 摘要：In the early 1970s,Ibach carried out low-energy electron diffraction experiments on ZnO and other semiconductor surface.Sak,Evans and Mills studied theoretically the surface polaron in polar crystals first and the Hamiltonian of the electron-surface phonon interaction was derived.Mills indicated that when electron moves in the surface vicinity of the crystals,the electron-surface-optical-phonon interaction produces a plarization cloud at the electron around,whereas because of the electron-surface acoustic phonon coupling the electron have been trapped at the surface vicinity motion.Theoretical results showed that the surface layer of crystals may be regarded as pure 2D crystals if the distance from the surface is smaller than the radius of polarions.The effect of bulk phonons can be neglected,while surface acoustic and surface optical phonons are taken into account in the surface layer.Veba discussed the properties of the electron,which is a interaction with both the surface optical and acoustic phonons in the surface phonon field.Toyozawa studied the quasi particle,the acoustic deformation potential(ADP)plaron,formed by the interaction of electrons with acoustic lattice vibration using the concept of the deformation potential.Recently Zhao Cui-lan et al. investigated the properties of surface polaron of interaction with the deformation potential.From the point of view of confined electron,studying electron via the deformation potential interaction with acoustic phonon is more significant.The properties of surface polaron in polar crystals,which is a weak coupling with surface optical and surface acoustic phonons,was studied.The effective Hamiltionian of the surface polaron is derived by using linear combination operator and unitary transformation.关键词：surface polaron;weak-coupling;effective Hamiltonian97|107|0更新时间：2020-08-11
- 摘要：For BAM,a serious thermal degradation takes place after annealing in air.The same BAM phosphors may exhibit a large difference in different annealing processes.It is known that thermal degradation of BAM is relevant to annealing process. Since in PDP and fluorescent lamp manufacturing processes the phosphor is heated in air or oxygen containing gas at 600℃ to make phosphor layer,it is important to show effect of oxygen concentration in gas and mechanism of thermal degradation of BAM. In this paper a model of thermal degradation of the blue emitting BaMgAl10O17:Eu(BAM)phosphor is presented to disclose effect of oxygen concentration on luminance decrease, ΔZ,in BAM after annealing in oxygen containing gas. According to the model,ΔZ is proportional to one sixth power of oxygen partial pressure,(PO2)1/6,and satisfies the following equation:ΔZ=α(PO2)1/6+β There,α is a temperature dependent parameter and increases with temperature,and β has the value of ΔZ as PO2=0.The experimental results of thermal degradation of BAM in gas with different oxygen concentrations at different temperatures were simulated by using the above equation.We got the formulae of ΔZ at 600℃,615℃,675℃ as follow:600℃:ΔZ=0.85(PO2)1/6+6.35 615℃:ΔZ=1.05(PO2)1/6+6.06 675℃:ΔZ=1.62(PO2)1/6+5.28 This stiumlation results indicate that 1) when O2%<10%,PO2 has much effect on ΔZ ; and however, when O2%>10%,PO2 has little effect on ΔZ,finally,ΔZ approaches to 12% at 600℃,13.5% at 615℃ and 17% at 675℃;2)with increasing temperature, the temperature dependent parameter α increases and the thermal degradation of BAM increases.关键词：phosphor;thermal degradation;rare earths;aluminate101|83|6更新时间：2020-08-11
- 摘要：Zn2-xSiO4:x Mn phosphors were synthesized at 1300℃ by high-temperature solid state reaction with silicic acid. X-ray powder diffraction data of Zn2-xSiO4:x Mn are in agreement with those of the JSPDS 37-1485 standard card, indicating that silicic acid is a good starting material for the synthesis of Zn2SiO4:Mn. Vacuum UV excitation and emission spectra were studied in detail. Considering the absorption from O2- 2p orbital to Si4+ 3p orbital transition and that from O2- 2p orbital to Zn2+ 3d orbital transition in the compounds, the absorption in the range from 200nm to 300nm may be mainly due to O2- 2p orbital to Zn2+ 3d orbital transition, the absorption below 190nm may be mainly assigned to O2- 2p orbital to Si4+ 3p orbital transition. The absorption peaks at about 346nm, 386nm,420nm,440nm,and 480nm are due to 6A1→4D, 4G transition, respectively. The emission spectrum under 254nm excitation consists of a band peak at about 525nm, this band is attributed to 4T1→6A1 transition. Considering the positions of Mn2+ emission in different hosts, it reveals that Mn2+ ions occupy tetrahedral sites. This result is in good agreement with surroundings of Zn2+ ions, indicating that Mn2+ ions replace Zn2+ ions in the host. The relationship between the emission intensity and the concentration of Mn2+ under VUV and UV excitation was also investigated. It was also found that the Mn2+ concentration of the maximum emission under 147nm excitation is about 0.07, that of the maximum emission under 200nm excitation about 0.08, and that of the maximum emission under 254nm excitation about 0.10. This result shows that the mechanism on luminescent quench under VUV excitation is different from that of on luminescent quench under UV excitation. This result indirectly reveals that the absorption band peak at about 240nm is due to O2- 2p orbital to Zn2+ 3d orbital transition.关键词：Zn2SiO4：Mn;VUV spectral property;quenching concentration of Mn2+ ions94|77|3更新时间：2020-08-11
- 摘要：The excitation and diffusion reflection spectra of GdVO4:Eu3+ were measured at room temperature. The influences of the doping method and sintering atmosphere on the excitation spectrum of GdVO4:Eu3+ were studied. The blue shift and intensity proportion change of the excitation bands, which are due to the effects of acid and deduced sintering atmosphere, are interpreted, the source of the bands at 200～350nm and the possible energy transfer of GdVO4:Eu3+ were discussed. The polycrystalline GdVO4:Eu3+ was prepared by the high-temperature solid reaction. Using X-ray diffraction (XRD) data, the lattice parameters a=7.22 and c=6.38 were calculated by the least square method, calculation gives the estimation density DX of XRD and DX=5.34 (g/cm3).关键词：GdO4：Eu3+;excitation spectrum;charge transfer transition;energy transfer86|161|6更新时间：2020-08-11
- 摘要：Er3+:Yb3+ doped oxy-fluoride glass was prepared.Four bands of unconverted emissions have been observed under excitation of a He-Ne laser with wavelength of 632.8nm through a R-500 spectrophotometer.The up-conversion mechanism was discussed, and the transfer and back-transfer between Er3+ and Yb3+ were used to explain the appearance of strong violet emission.关键词：rare earth doping;energy up-conversion88|95|6更新时间：2020-08-11
- 摘要：Langmuir-Blodgett(LB)film technique makes it possible to prepare organic functional ultrathin films with a controlled thickness at a molecular size and well-defined molecular orientation.Therefore,if any electroluminescent(EL)materials can be incorporated in LB films,the films will be fabricated more conveniently than by general vacuum deposited technique and may have potential applications in molecular electronic devices.In the EL devices with LB films as emitting layer,the constitute and thickness of the emitting layer can be exactly controlled and this layer can be fabricated at room temperature and at atmospheric pressure.This paper reviews the LB films materials used as the emitting layers, hole-transporting materials and electron-transporting materials in EL devices.The influence of the number of the layers of LB films and the deposited surface pressure on the I-V characteristics,EL intensity,as well as break-down voltage of the EL devices are presented by taking amphiphilic 8-hydroxyquinoline complexes as examples.The existent problems and further development of EL devices with LB films as emitter are commented as a conclusion remark.关键词：Langmuir-Blodgett films;electroluminescence;devices95|99|3更新时间：2020-08-11
- 摘要：A blue organic light emitting diode (OLED) with rather stability was realized by using a new blue emitting material. In this device, copper phthalocyanine (CuPc) was chosen as a buffer layer, N,N’-bis-(1-naphthy1)-N,N’-diphenyl-1,1’-biphenyl-4-4’-diamine (NPB) was used as the hole transporting layer, 9,10-bis(3’5’-diaryl)phenyl anthracene (JBEM) was used as the emitting layer, in which peryrene was doped, then Alq was used as the electron transporting, MgAg alloy as the cathode. The structure of blue device was ITO/CuPc/NPB/JBEM:Peryrene/Alq/MgAg. Based on the blue device, a white device was constructed in which both perylene and DCJTB were doped in the emitting layer JBEM, the structure was ITO/CuPc/NPB/JBEM:Peryrene:DCJTB/Alq/MgAg. The luminance, chromaticity and EL spectra of the OLED cells were measured with PR-650 Spectrascan Spectra Colorimeter. The characteristic of current-voltage was measured by using a Keithley 2400 Source Meter. Operation of the encapsulated EL cell was conducted at room temperature using a DC voltage current source in the constant current mode. For the blue device, maximum luminance of 7526cd/m2, the luminance of 408cd/m2 under current density of 20mA/cm2, maximum efficiency 1.45 lm/W, the half decay time of 1035h at initial luminance of 100cd/m2 were achieved. The white OLED shows the CIE coordinates x=0.32, y=0.38 and the independence of CIE coordinates on the current density. The maximum luminance of 14852cd/m2,the luminance of 878cd/m2 under current density of 20mA/cm2, maximum efficiency of 2.88 lm/W and half decay time of 2860h at initial luminance of 100cd/m2 were obtained.102|113|1更新时间：2020-08-11
- 摘要：The calculation of dielectric correlation function in PbF2+WO3+GeO2(PWG)glass ceramics was proposed.It shows that Raman scattering selection-rules are broken by the short coherent length of the right vibrating modes in the disorder materials.Expression formula of first order Raman scattering intensity was derived and analyzed based on state density function and amplitude change of right vibrating mode with frequencies.关键词：glass ceramics;Raman scattering selection-rule;state density87|78|0更新时间：2020-08-11
- 摘要：The metabolic level of medications which treat cancer was studied by fluorescence spectroscopic analysis in the patients body, the medications were quantitatively analyzed in the urine that was simulated with water as solvent. The measuring conditions were discussed, including the effects of fluorescence quenching, sensitization medium and the medication concentration change. The method of quantitative analysis was researched for the medication metabolizing in body by fluorescence spectroscopy, and the sensitizing pattern between donor and acceptor of energy was discussed with Förster theory in this paper. The results show that fluorescence is quenched as the compound containing Fe# concentration is 1×10-4 g/mL in 1×10-7 g/mL HPD (hematoporphyrin); the luminescence intensity of poxorubicin hydrochloride is higher as its concentration is lower from contrasting concentration 1×10-3 g/mL to 1×10-4 g/mL for fluorescence and excitation spectra, respectively, and the spectra are shifting red or blue when the concentration quenching arise, then can get rid of the interference of concentration effect by changing the point of measuring luminescence intensity on the line area, and the fluorescence and excitation spectra of Poxorubicin Hydrochloride; Etoposide; Vincristinal Sulfas and Mitomycin-c for injection could also be obtained from this experiment. The detection limit of this method can achieve 10-3～10-7 g/mL, and this results show that detection sensitivity of fluorescence spectroscopy is higher than those of other analytic methods.关键词：treat medications for cancer;fluorescence spectrum;excitation spectrum86|86|2更新时间：2020-08-11
- 摘要：White LED has attracted considerable interest in recent years because of further improvement of “green lighting source” and micro solid state lighting source.It can be used for aerospace lighting, emergency and signal lighting,hazardous lighting,electronic signs,general industrial lighting.This paper considered the development of white LED for lighting source and compared our sample with foreign products.For the products of Nichia Corporation,the luminescent intensity is 5.5cd;the color coordinate is x=0.31,y=0.32;the color index is 85.For the products of Opto Technology Inc.,the luminescent intensity is 0.5 cd;the color coordinate is x=0.26,y=0.25;the color index is 48.For our sample,luminescent intensity is 1.4 cd;the color coordinate is x=0.30,y=0.28;the color index is 89.关键词：white lighe;LED123|136|9更新时间：2020-08-11
- 摘要：High quality ZnO thin films were prepared by plasma enhanced chemical vapor deposition from the metal organic and carbon dioxide mixture gas sources.The wurtzite structure of ZnO thin films with a strong c axis orientation was successfully grown on the (001)Si substrate.The structure and composition were characterized by using X-ray diffraction and atomic force microscope(AFM)image.A type excition absorption line of ZnO was observed from optical transmission spectra.This method has a promise advantage in preparing high quality ZnO thin film.关键词：ZnO;thin film;PECVD89|88|1更新时间：2020-08-11
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