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1.
We analyze the effect of the spatial correlation on the ground state energy of two particles (two electrons and exciton–hole pair) confined in quantum ring (QR) with a soft-edge-barrier confinement potential. Starting from the Schrödinger variational principle we derive a one-dimensional differential equation for the spatial pair correlation function (SPCF), which we solve numerically by using the shooting method. The effect of the repulsive core in a self-assembled GaAs/InAs QR on the two-electron and exciton SPCF is analyzed. A comparative analysis of the dependencies of the two-particle ground state energies on the inner and outer radii of GaAs/InAs QRs with different confinement potential shapes is presented.  相似文献   

2.
Analytical solutions of electronic wave functions in symmetric quantum ring (QR), quantum wire (QWR) and quantum dots (QD) structures are given using a parabolic coordinates system. The solutions for low-energy states are combinations of Bessel functions. The density of states of perfect 1D QR and QWR are shown to be equivalent. The continuous evolution from a 0D QD to a perfect 1D QR can be precisely described. The sharp variation of electronic properties, related to the build up of a potential energy barrier at the early stage of the QR formation, is studied analytically. Paramagnetic and diamagnetic couplings to a magnetic field are computed for QR and QD. It is shown theoretically that magnetic field induces an oscillation of the magnetization in QR.  相似文献   

3.
Using a numerical method via the electron effective mass theory, a model of a quantum ring (QR) with a shape very close to the real one and taken from an experimental work, we investigate the electron states in a semi-conductor QR, studying the influence of the ring’s geometrical parameters on the electron spectrum and on the optical transitions. Our hetero structure evolves from a single quantum dot (QD) to a QR. We find that the one-electron ground state presents an absolute minimum when studied as a function of the ring radius. The reliability of the calculations is checked with experimental data.  相似文献   

4.
The electronic properties of CdTe/ZnTe quantum rings (QRs) are investigated as functions of size and temperature using an eight-band strain-dependent k·p Hamiltonian. The size effects of diameter and height on the strain distributions around the QRs are studied. We find that the interband transition energy, defined as the energy difference between the ground electronic and the ground heavy-hole subbands, increases with the increasing QR inner diameter regardless of the temperature, while the interband energy decreases with the increasing QR height. This is attributed to the reduction of subband energies in both the conduction and the valence bands due to the strain effects. Our model, in the framework of the finite element method and the theory of elasticity of solids, shows a good agreement with the temperature-dependent photoluminescence measurement of the interband transition energies.  相似文献   

5.
Herein, we report a one-pot synthesis of structurally uniform and electrochemically active graphitic carbon nitride/nickel oxide (g-C3N4/NiO) nanocomposite and an investigation on the electrocatalytic oxidation of quercetin (QR). The synthesized g-C3N4/NiO nanocomposite has uniform surface distribution, which was characterized with scanning electron microscopy (SEM). Moreover, the composition of synthesized g-C3N4/NiO nanocomposite was characterized by UV–vis-spectroscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR spectra), BET, SEM and HRTEM. The g-C3N4/NiO was electrochemically treated in 0.1 MPBS solution through cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The peak current response increases linearly with QR concentration from 0.010 μM to 250 µM with a fast response time of less than 2 s and a detection limit of 0.002 μM. To further evaluate the feasibility of using this sensor for real sample analysis, QR content in various real samples including green tea, green apple, honey suckle were determined and satisfactory results were achieved.  相似文献   

6.
We change the ellipsoidal boundary in a quantum rod (QR) into a spherical one by a coordinate transformation, and then study the influences of the ellipsoid aspect ratio and polaron radius on the probability density (PD) and oscillation period (OP) of an electron with the variational method of Pekar type (VMPT). By employing the quantum statistics theory (QST), we investigate the temperature effects on the PD and the OP. Numerical results denote that the electron probability density and the oscillation period increase (decay) with raising temperature in lower (higher) temperature regime. The electron probability density increases (decreases) with increasing ellipsoid aspect ratio when the temperature is in lower (higher) regime. The electron probability density decays (enhances) with increasing polaron radius when the temperature is in lower (higher) temperature regime. The oscillation period is an increasing function of the ellipsoid aspect ratio, whereas it is a decreasing one of the polaron radius.  相似文献   

7.
利用(e,2e)电子动量谱学手段首次测量了乙硫醇分子全部价轨道的束缚能谱和电子动量分布. 谱仪采用非共面对称的运动学条件,入射电子能量为1.2 keV加束缚能. 实验结果与密度泛函和Hartree-Fock方法的理论计算结果基本相符. 在束缚能谱中,观察到了17.8 eV的可能的伴线,并用电子动量谱进行了研究和标识.  相似文献   

8.
Explosive detection machines on the basis of quadrupole resonance (QR) technology are under development for land mine detection and other antiterrorism applications. The QR machines are optimized to detect the actual explosive ingredient in a detonable formulation and to ignore signals from other, benign materials. This presents a safety and logistical challenge for QR land mine detector testing and calibration because of the hazards involved when handling even small amounts of a detonable explosive. The detonation hazard can be mitigated by adding inert materials (desensitizers) to coat the crystalline explosive. The effect on the QR signal of various types of inert material is examined, with a view to developing a safe QR land mine target.  相似文献   

9.
A Smith–Purcell (S–P) free electron laser (FEL) composed of a metallic diffraction flat grating, an open cylindrical mirror cavity and a relativistic sheet electron beam with moderate energy, is presented. The characteristics of this device are studied by theoretical analysis, experimental measurements and particle-in-cell (PIC) simulation method. Results indicate that coherent radiation with output peak power up to 50 MW at millimeter wavelengths can be generated by using relativistic electron beam of moderate energy.  相似文献   

10.
The spatial distributions of the electron density and the mean electron energy of argon radio frequency (rf) glow discharge plasma in a plasma-enhanced chemical vapour deposition (PECVD) system have been investigated using an established movable Langmuir probe. The results indicate that in the axial direction the electron density tends to peak at midway between the two electrodes while the axial variation trend of mean electron energy is different from that of the electron density, the mean electron energy is high near the electrodes. And the mean electron energy near the cathode is much higher than that near the anode. This article focuses on the radial distribution of electron density and mean electron energy. A proposed theoretical model distribution agrees well with the experimental one: the electron density and the mean electron energy both increase from the centre of the glow to the edge of electrodes. This is useful for better understanding the discharge mechanism and searching for a better deposition condition to improve thin film quality.  相似文献   

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