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The nonrelativistic oscillator strength of a hyperbolic-type potential

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Chinese Physics B 2013年第6期22卷 105-109页

作者： H.Hassanabadi S.Zarrinkamar B.H.Yazarloo Department of Basic Sciences Shahrood BranchIslamic Azad UniversityShahroodIran Department of Basic Sciences Garmsar BranchIslamic Azad UniversityGarmsarIran

We consider the D-dimensional SchrSdinger equation under the hyperbolic potential V0（1 -coth（ar））＋ 171 （1 - coth（ar））2. Using a Pekeris-type approximation, the approximate analytical solutions of the problem are obtained via the supersymmetric quantum mechanics. The behaviors of energy eigenvalues versus dimension are discussed for various quantum numbers. Useful expectation values as well as the oscillator strength are obtained.

关键词： Schroedinger equation D-dimensional space hyperbolic potential supersymmetry quantum me-chanics oscillator strength

Absolute oscillator strength densities below 100eV of N2

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Chinese Physics B 2005年第7期14卷 1378-1381页

作者：孙建敏钟志萍朱林繁刘小井苑震生徐克尊 HefeiNationalLaboratoryforPhysicalSciencesatMicroscale DepartmentofModernPhysicsUniversityofScienceandTechnologyofChinaHefei230026China DepartmentofPhysics GraduateSchooloftheChineseAcademyofSciencesBeijlng100039China

The absolute optical oscillator strength density (OOSD) and generalized oscillator strength densities (GOSDs)below 100eV of N2 are determined with an incident electron energy of 2500eV and an energy resolution of 100 meV.The absolute generalized oscillator strengths (GOSs) for two transitions to the superexcited states at 23 and 31.4eV are determined and their momentum transfer dependence behaviours are discussed.

关键词： oscillator strength superexcited state energy-loss spectrum

Hybridized Local and Charge-Transfer Excited-State Fluorophores through the Regulation of the Donor-Acceptor Torsional Angle for Highly Efficient Organic Light-Emitting Diodes

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CCS Chemistry 2022年第4期4卷 1284-1294页

作者： Xiaojie Chen Dongyu Ma Tiantian Liu Zhu Chen Zhan Yang Juan Zhao Zhiyong Yang Yi Zhang Zhenguo Chi PCFM Lab GD HPPC LabGuangdong Engineering Technology Research Centre for High-Performance Organic and Polymer Photoelectric Functional FilmsState Key Laboratory of Optoelectronic Materials and TechnologiesSchool of ChemistrySun Yat-sen UniversityGuangzhou 510275 State Key Laboratory of Optoelectronic Materials and Technologies School of Materials Science and EngineeringSun Yat-sen UniversityGuangzhou 510275

Hybridized local and charge-transfer(HLCT)excitedstate fluorophores,which enable full exciton utilization through a reverse intersystem crossing fromhigh-lying triplet states to singlet state,have attracted increasing attention toward organic light-emitting diodes(OLEDs)application.Herein,we report three D-π-A-π-D-type isomers o-2CzBT,m-2CzBT,and p-2CzBT by adjusting the donor(D)units from ortho-,meta-,to para-substituted positions with the acceptor(A)core unit,respectively.The HLCT properties of the three compounds are evidently confirmed by theoretical calculations,solvatochromic behaviors,and transient decay lifetimes analyses.As the substituted position changes from the ortho-,meta-,and para-positions,the reduced steric hindrance brings about decreased torsional angle between D and A moieties,resulting in increased oscillator strength.Accordingly,the parasubstituted p-2CzBT is endowed with a more locally excited component that accounts for faster radiative decay,leading to a higher fluorescent efficiency than that of o-2CzBT and m-2CzBT.As expected,p-2CzBT enables its nondoped and doped OLEDs with higher external quantum efficiencies(EQEs)of 12.3% and 15.0%,respectively,which are among the state-ofthe-art efficiencies of HLCT-based OLEDs.Moreover,o-2CzBT and m-2CzBT are also utilized as host materials for high-performance OLEDs,thus extending the application of HLCT materials.

关键词： hybridized local and charge-transfer torsional angle oscillator strength high efficiency OLED

Design and simulation to improve the structural efficiency of green light emission of GaN/InGaN/AIGaN light emitting diode

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Frontiers of Optoelectronics 2017年第4期10卷 370-377页

作者： Sakhawat HUSSAIN Tasnim ZERIN Md. Ashik KHAN Department of Electrical and Electronic Engineering University of Dhaka Dhaka-1000 Bangladesh

This study considered the design of an efficient, high brightness polar InGaN/GaN light emitting diode （LED） structure with A1GaN capping layer for green light emission. The deposition of high In （〉 15%） composition within InGaN quantum well （QW） has limitations when providing intense green light. To design an effective model for a highly efficient InGaN green LEDs, this study considered the compositions of indium and aluminum for InxGal xN QW and AlyGal yN cap layers, along with different layer thicknesses of well, barrier and cap. These structural properties significantly affect different properties. For example, these properties affect electric fields of layers, polarization, overall elastic stress energy and lattice parameter of the structure, emission wavelength, and intensity of the emitted light. Three models with different composition and layer thicknesses are simulated and analyzed to obtain green light with in-plane equilibrium lattice parameter close to GaN （3.189 A ） with the highest oscillator strength values. A structure model is obtained with an oscillator strength value of 1.18 × 10-1 and least in-plane equilibrium lattice constant of 3.218 A. This emitter can emit at a wavelength of 540 nm, which is the expected design for the fabrication of highly efficient, bright green LEDs.

关键词： green light emitting diode （LED） latticeparameter oscillator strength InGaN quantum well （QW）,A1GaN capping layer

Radiative life time of an exciton confined in a strained GaN/Ga_(1-x)Al_xN cylindrical dot:built-in electric field effects

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Chinese Physics B 2011年第7期20卷 367-372页

作者： Chang Woo Lee A.John Peter Department of Chemical Engineering and Green Energy Center College of EngineeringKyung Hee University1 SeochunGihungYonginGyeonggi 446-701Republic of Korea Department of Physics Government Arts and Science CollegeMelur-625106India

The binding energy of an exciton in a wurtzite GaN/GaAlN strained cylindrical quantum dot is investigated theoretically. The strong built-in electric field due to the spontaneous and piezoelectric polarizations of a GaN/GaAlN quantum dot is included. Numerical calculations are performed using a variational procedure within the single band effective mass approximation. Valence-band anisotropy is included in our theoretical model by using different hole masses in different spatial directions. The exciton oscillator strength and the exciton lifetime for radiative recombination each as a function of dot radius have been computed. The result elucidates that the strong built-in electric field influences the oscillator strength and the recombination life time of the exciton. It is observed that the ground state exciton binding energy and the interband emission energy increase when the cylindrical quantum dot height or radius is decreased, and that the exciton binding energy, the oscillator strength and the radiative lifetime each as a function of structural parameters （height and radius） sensitively depend on the strong built-in electric field. The obtained results are useful for the design of some opto-photoelectronic devices.

关键词： quantum dot donor bound excitons oscillator strength

The nonlinear optical properties of a magneto-exciton in a strained Ga_(0.2)In_(0.8)As/GaAs quantum dot

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Chinese Physics B 2013年第10期22卷 479-485页

作者： N.R.Senthil Kumar A.John Peter Chang Kyoo Yoo Department of Physics SBM College of Engineering and Technology Department of Physics Govt.Arts CollegeMelur-625 106MaduraiIndia Center for Environmental Studies/Green Energy Center Deptartment of Environmental Science and EngineeringCollege of EngineeringKyung Hee UniversitySeocheon-dong 1Giheung-guYongin-SiGyeonggi-Do446-701South Korea

The magnetic field-dependent heavy hole excitonic states in a strained Gao.2Ino.sAs/GaAs quantum dot are investi- gated by taking into account the anisotropy, non-parabolicity of the conduction band, and the geometrical confinement. The strained quantum dot is considered as a parabolic dot of InAs embedded in a GaAs barrier material. The dependence of the effective excitonic g-factor as a function of dot radius and the magnetic field strength is numerically measured. The interband optical transition energy as a function of geometrical confinement is computed in the presence of a mag- netic field. The magnetic field-dependent oscillator strength of interband transition under the geometrical confinement is studied. The exchange enhancements as a function of dot radius are observed for various magnetic field strengths in a strained Gao.2Ino.sAs/GaAs quantum dot. Heavy hole excitonic absorption spectra, the changes in refractive index, and the third-order susceptibility of third-order harmonic generation are investigated in the Gao.2Ino.8As/GaAs quantum dot. The result shows that the effect of magnetic field strength is more strongly dependent on the nonlinear optical property in a low-dimensional semiconductor system.

关键词： oscillator strength exciton quantum dot

Optical properties of ionized donor-bound excitons confined in strained wurtzite ZnO/Mg_xZn_(1-x)O quantum dots

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Journal of Semiconductors 2015年第3期36卷 46-51页

作者：郑冬梅王宗篪肖波齐 College of Electromechanical Engineering Sanming University

Within the framework of the effective-mass approximation and the dipole approximation, considering the three-dimensional confinement of the electron and hole and the strong bulk-in electric field （BEF） in strained wurtzite ZnO/Mgo.25Zno.750 quantum dots （QDs）, the optical properties of ionized donor-bound excitons （D^＋, X） are investigated theoretically using a variational method. The computations are performed in the case of finite band offset. Numerical results indicate that the optical properties of （D^＋, X） complexes sensitively depend on the donor position, the QD size and the BEF. The binding energy of （D^＋, X） complexes is larger when the donor is located in the vicinity of the left interface of the QDs, and it decreases with increasing QD size. The oscillator strength reduces with an increase in the dot height and increases with an increase in the dot radius. Furthermore, when the QD size decreases, the absorption peak intensity shows a marked increment, and the absorption coefficient peak has a blueshift. The strong BEF causes a redshift of the absorption coefficient peak and causes the absorption peak intensity to decrease remarkably. The physical reasons for these relationships have been analyzed in depth.

关键词： ZnO quantum dot ionized donor-bound exciton binding energy oscillator strength absorption coefficient

Effect of Different Ligand Field strengths on the oscillator strengths of Lanthanide Ions

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Journal of Rare Earths 1998年第1期16卷 6-10页

作者：武登国孙元洪李国柱 Department of Chemistry Inner Mongolia University Hohhot 010021 China

The oscillator strengths of the absorption spectra for rare earth complexes in different solvents were determined and calculated on the basis of the JuddOfelt theory. The effect of different ligand field strengths on the oscillator strengths of lanthanide ions is discussed. In plotting the oscillator strengths of the hypersensitive transition of Ho3+, Er3+ against those of Nd3+, the reverse extending lines of the straight lines were found to intersect at a point on the whole. The coordinates of the crosspoint are believed to represent the strength value of the smallest coordinated effect.

关键词： Rare earths Rare earth complexes Hypersensitive transitions oscillator strength

Study on F-F Transitions of Powdered Neodymium Compounds by Photoacoustic Spectroscopy

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Journal of Rare Earths 2002年第1期20卷 10-14页

作者：杨跃涛苏庆德赵贵文张淑仪 StateKeyLaboratoryofModernAcoustics InstituteofAcousticsNanjingUniversityNanjing210093 China DepartmentofChemistry UniversityofScienceandTechnologyofChinaHefei230026China

Photoacoustic (PA) spectra of powdered neodymium oxide (Nd 2O 3 (A type)), neodymium hydrated chloride (NdCl 3·6H 2O) and neodymium fluoride (NdF 3) were reported. PA band shifts as compared to their positions in aqueous Nd 3+ are used to calculate the nephelauxetic parameters of the compounds. The variation of these parameters and correlation with the nature of metal ligand bonding were discussed. A novel method is introduced to determine the relative values of oscillator strengths and Judd Ofelt parameters of powdered samples using PA spectroscopy. It is found that a linear correlation exists between relative values of τ 2 and oscillator strengths of hypersensitive transitions of the title compounds. It is hopetul that the new method of PA technique may serve for the Judd Ofelt quantitative analysis of powdered rare earth compounds.

关键词： rare earths photoacoustic spectroscopy neodymium f f transition oscillator strength