最新刊期
卷 17 ， 期 4 ， 1996
- 摘要：Monte Carlo simulation has been carried out to get the free induction decay and photon echo decay for a system of A spins, isolated from each other, whose resonant frequency fluctuates because of the flipping of a surrounding B spins. We find that the decay line shape is dependent only on k, the ratio of the frequency fluctuation amplitude and twice of the average flip rate. The simulated photon echo decay can be expressed asexp[-(4τ/tm)x] where x ranges from 1 to 3. Nonexponential echo decay in ruby is alsodiscussed qualitatively.关键词：dephasing;Monte Carlo simulation;free induction decay;photon echo123|72|0更新时间：2020-08-11
- 摘要：The photoacoustic spectral study of energy transfer between two rare earth ions in phosphor are first reported. Combined with photoluminescent spectra (PLS) and photoacoustic spectra (PAS), the mechanism of sensitization of Ce3+ to Tb3+ and quenching of Tm3+ to Er3+ in LaOBr are discussed. In phosphor LaOBr:Tb, Ce,under 365nm excitation, the emissions of Tb3+are enhanced obviously by Ce3+, and the photoacoustic peak of Ce3+ increases. It suggests that the sensitization of Ce3+ to Tb3+ is phonon assisted energy transfer. In LaOBr:Er, Tm system, the visible emission (green:4S3/2-4I15/2, red:4F9/2-4I15/2) of Er3+ are quenched by co-doped Tm3+. Among four main photoacoustic peaks of Er3+, the intensities of PA peaks at 527nm and 646nm which correspond to the absorption of energy levels 2H11/2 and 4F9/2 of Er3+ respectively increase obviously with Tm3+ while other two (372nm and 486nm )keep constant. Our results not only confirm that the cross relaxation of Er3+:4S3/2-4F9/2,11/2 and Tm3+:3H6-3H4,5 causes the quenching of visible emissions of Er3+, but also suggest that there exists another cross relaxation of Er3+:4F9/2-4I13/2 and Tm3+:3H6-3H5 which raises the quenching of red emission of Er3+.关键词：Photoacoustic spectra;energy transfer;LaOBr110|124|0更新时间：2020-08-11
- 摘要：In this paper, we present a full explanation for the average-bond-energy (ABE) model, which was developed, on the basis of numerical calculations, for the determination of valence-band offsets at heterointerfaces. By comparing it with the TB" pinned" model, the dielectric-midgap-energy model, and the charge-neutrality-point model, the relations between the four model theories are shown, and the advantages and limitationsof the ABE model are discussed. In this paper, the ABE model is applied to determining the valence-band offsets at 27 lattice-matched heterointerfaces systematically. The results show:(1)the cation shallow d orbitals play an important role in determining the theoretical values of valence-band offsets; (2)the interface dipole potential is an important contribution to the valence-band offset; (3)the results of ABE model are in good agreement with relevant experimental data, and the accuracy seems to be better than that of several other model theories; (4)the ABE model is not suitable to material systems which do not possess the character of sp3 hybridization.关键词：band offsets;semiconductor heterointerfaces;ab initio calculations98|79|1更新时间：2020-08-11
- 摘要：The mechanism of the near-band-gap optical transition in doped SiGe/Si quantum well is investigated, and the model of the near-band-gap optical transition originated from the statistical distribution of the impurities is suggested. The dipole matrix elements of the transition are calculated based on this model and the upper limits of the dipole matrix elements are also calculated. The mechanism of the near-band-gap optical transition in undoped SiGe/Si quantum well is also suggested that it is the collective action of the deformation wavefunction around Ge atoms. The samples of doped SiGe/Si quantum well have been grown using a molecular beam epitaxy (MBE) system and the near-band-gap optical transition from these samples was observed at low temperatures.关键词：SiGe/Si quantum well;optical transition120|94|1更新时间：2020-08-11
- 摘要：The colour changeable ZnS:Mn/SrS:Ce/ZnS:Mn thin film electroluminescence devices have been prepared. The dependence of the electroluminescent emission spectra on applied voltage and frequency was studied and the reason of the different increase of the blue band and yellow band of the electroluminescent emission spectra was disscused. The reason of the different dependence of the blue band and yellow band of the electroluminescent emission spectra on frequency under different voltage was aslo disscussed.关键词：ZnS：Mn/SrS：Ce/ZnS：Mn;thin film electroluminescence101|76|4更新时间：2020-08-11
- 摘要：The hot electron energy was obviously increased by inserting SiO2 layers into the central part of the luminescent layer in the layered optimized TFEL devices. But the improvement of brightness and efficiency was dependent on the crystallinity of the active layer. The green emission intensity and efficiency of the sample with two active layers were higher than that of the one-active-layer sample, while they were decreased greatly in the 3-active-layer sample due to the poor quality of the active layer.关键词：layered optimization;hot electron energy;green emission intensity;crys-tallinity86|75|1更新时间：2020-08-11
- 摘要：When the ultrasonic wave is applied to a 4mm ferroelectric semiconductor 180° domain sandwich structure, the ferroelectric domain layer wave (FDLW) will be induced. The electric potential fields of FDLW make the electrons and holes in the domain structure separate and compound continuously, the light pulse will be emitted, transforming the ultrasonic energy into light energy. Modulating the ultrasonic wave, intensity and period of the light pulse will change.关键词：ferroelectric domain;ultrasonic wave;acoustoluminescence94|82|0更新时间：2020-08-11
- 摘要：The blue-emitting phosphor SrGa2S4:Ce was prepared, whose crystallinity was analysed by X-ray diffraction. The excitation and emission spectra of SrGa2S4:Ce were measured and investigated, and the effects of the cerium concentration on the PL properties of SrGa2S4:Ce powder wrer studied. The results of PL measurement showed that SrGa2S4:Ce phosphor achieved an even more saturated blue emission, and the optimum cerium concentration for high efficiency and more saturated blue emission was ranged from 3.0 to 4.0 mol%.关键词：SrGa2S4：Ce;photoluminescence;blue-emitting phosphor80|113|2更新时间：2020-08-11
- 摘要：In this paper, The field in the phosphor of a TFEL device vs. applied voltage characteristic is investigated by Franz-Keldysh effect. The field strength in the phosphor calculated using this method has difference in numerical value compared with that estimated by the methods of every layer only acting as insulating layer though they are in the same order. The difference is even bigger at the threshold voltage.关键词：electroluminescence;Franz-Keldysh effect107|77|0更新时间：2020-08-11
- 摘要：The silicon tips array was fabricated using isotropic etching. The fabricated condition affecting the shape of tips were researched.关键词：vacuum microelectronics;field emission;silicon tips array;SEM93|91|2更新时间：2020-08-11
- 摘要：Er and O have been coimplanted in silicon. Rutherford backscattering and channeling analysis show that after annealing the Er profiles are different for the samples with various O doses. For the sample of high O dose, after annealing Er profile is same as the one before annealing, and the sample recrystallization is perfect. For the sample of middle O dose,, after annealing Er profiles present two peaks. We consider that Er-O complexes form during annealing. The formatiom of complexes reduces the Er segregation and diffusivity and influences the Er redistribution profiles. A series of experiments of Er and O implantation doses confirm the crucial role of O in increasing Er3+ luminescence.关键词：erbium;silicon;backscattering analysis;luminescence120|81|1更新时间：2020-08-11
- 摘要：Plasma polymerized polymers (polynaphthalene and polyanthrance) showing photo-luminescence (PL) have been synthesised. The PL characteristic can be changed by the reaction condition. For example,the polynaphthalence fluorescence peak varies from 415 nm to 550 nm by changing the input power. Using polynaphthalence as emitting layer, the light emitting device(LED)has also been made (Al/Polymer/ITO), which show the similar characteristic to its PL. Further study demonstrates that both PL and EL characteristic are due to the several chromophores in the polymer.关键词：photoluminescence;electroluminescence;plasma polymerization;LED85|76|0更新时间：2020-08-11
- 摘要：2-styrylbenzothiazole(2-SBT) compounds with acetoxy were synthesized, and theluminescence properties of the compounds were studied in this paper. The results indicated that the acetoxy exhibits typically electronic characteristics. At toluene solution the acetoxy is donor and addition of an acetoxy in the 2-SBT molecule causes a red shift of longest excitation band and luminescence spectra because of interaction between thedonor and the acceptor in compounds Ⅱ,Ⅲ, Ⅳ. However, at solid state the acetoxy isacceptor and the blue-shift of the luminescence spectra of 2-SBT with acetoxy in comparison with the spectra of 2-SBT due to the intramolecular hydrogenbonding.关键词：acetoxy;2-SBT;fluorescence property90|80|1更新时间：2020-08-11
- 摘要：Organic EL devices having Tb3+ complex as an emitter have been reported by our group. In this paper we examine the properties of organic EL device with diamine as a hole transport layer, TPD:N,N’-diphenyl-N,N’-(3-methyl)phyla-1,1’-4,4’-biphenyl-4,4’-diamine. Stronger Tb3+ EL emission with lower blue emission from HTL layer was obtained. It is also found that the devices have better I-V character and lower threshold voltage.关键词：organic luminescent diode;organic material Tb(AcA)3 ·phen93|71|7更新时间：2020-08-11
- 摘要：Based on the Inner Filter Effect (IFE) i. e. the fluorescence of a fluorescent compound is perturbed by a non-fluorescent analyte,an accurate and specific fluorescence spectroscopy method determinating nitric oxide (NO) was established. NO level of normal wistar rat brain is 938±156 pmol/mg protein.关键词：nitric oxide (NO);fluorescence spectroscopy;brain tissue135|82|3更新时间：2020-08-11
- 摘要：Rubrene is doped into the hole transport layer of an organic thin film electroluminescent (OTFEL) device with a double-layered structure. It is found that the dopant has profound influences on the EL characteristics. It changes the region of light emission and thus the EL spectrum, increases the luminescence efficiency by more than 50% and improves the device stability by 10 times. The effect of the dopant on the energy relation of the materials discussed.121|59|4更新时间：2020-08-11
- 摘要：The degradation properties of the Organic Thin Film Electroluminescent (OTFEL) devices consisting of a Alq(as a light-emitting layer) and PVK (as a hole-transporting layer) were studied in an ambient temperature.Under a constant pulse voltage driving, we found a very interesting EL forming phenomenon for the first time:at the initial step of the operating process, the luminance and current density increase first, reach maximum, then decrease. The mechanism of the forming process being investigated.104|81|0更新时间：2020-08-11
- 摘要：The photoluminescence peaked at about 1.69 eV of C60 doped by the sol-gel method was studied as a function of temperatures at 30-200 K. The peak positions were slightly shifted to red side and photoluminescence intensities were strongly decreased with increasing temperatures. A turning point in photoluminescence intensities-temperature curve was observed. The turning point was caused by the defects due to the thermal strain and the ratcheting motion of C60 molecules. The activation energy of the photoluminescence centers, 475 cm-1 was obtained by fitting the experimental data.103|63|0更新时间：2020-08-11
- 摘要：In Eu(NO3)3phen:PVK system, energy transfer from PVK to Eu(NO3)3phen was found. The electroluminescent devices using Eu(NO3)3phen as the emitter were fabricated. For the first time, we obtained the characteristic EL emissions from Eu3+of Eu(NO3)3phen emitter in the OEL cell.107|55|2更新时间：2020-08-11
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