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101.
S. Kang Y.-M. Liu T.-Y. Shi 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,63(1):37-42
The energy spectra of H2
+-like impurities confined in
finite spherical quantum dots have been calculated as a function
of the distance between nuclear with different sizes on the basis
of effective-mass approximation by linear variational method.
B-splines have been used as basis functions, which can easily
construct the trial wavefunctions with appropriate boundary and
cusp conditions. The quantitative analyses of the partial wave
weights for ground state and some low lying states have been done. 相似文献
102.
Desmond Macleod-Carey Giovanni F. Caramori Raúl Guajardo-Maturana Dayan Paez-Hernandez Alvaro Muñoz-Castro Ramiro Arratia-Perez 《International journal of quantum chemistry》2019,119(2):e25777
The inclusion of relativistic effects to understand chemical structures and related properties brings to the scientific community challenging study cases, showing the rich diversity of chemical behavior of the different elements along the periodic table. The results highlighted here represent applications of relativistic methodologies to study the nature of bonding and a prediction of optical and magnetic properties of meaningful chemical entities containing heavy atoms, all made in Latin America. The good agreement between calculated and experimental observables in many molecular and cluster-like systems ratifies that relativistic methods are appropriate to describe these entities realistically. We expect to enhance our knowledge in these methodologies, currently included in doctoral programs in our region. 相似文献
103.
The ground state and a few excited state energies of a hydrogenic donor in a quantum well are computed in the presence of pressure and temperature. The binding energies are worked out for GaAs/ Ga1−xAlxAs structures as a function of well size when the pressure and temperature are applied simultaneously. A variational approach within the effective mass approximation is considered. The results show that for a constant applied pressure, an increase in temperature results in a decrease in donor impurity binding energy while an increase in the pressure for the same temperature enhances the binding energy. When the pressure and temperature are applied simultaneously the binding energy decreases as the well width increases. In all the cases, it is observed that there is an increase in the binding energy due to the decrease in the quantum well size and in the dielectric constant whereas the effects of temperature on the effective mass are minimal. 相似文献
104.
The ground and excited states of a donor impurity at the center of a spherical quantum dot subject to a magnetic field are calculated within the effective-mass approximation. The barriers are infinitely high and the differential equation is solved by combining the finite-difference method with the Richardson extrapolation. The binding and transition energies are more accurate than the available variational values, and excellent agreement is found with the hydrogen atom. The transition energies for a medium-size quantum dot are given. 相似文献
105.
106.
Over the last two hundred years, there have been many occasions where the name of a newly-discovered element has provoked
controversy and dissent but in modern times, the naming of elements after scientists has proved to be particularly contentious.
Here we recount the threads of this story, predominantly through discourses in the popular scientific journals, the first
major discussion on naming an element after a scientist (Moseley); the first definitive naming after a scientist (Curie);
and the first naming after a living scientist (Seaborg). 相似文献
107.
Dr. Xianghe Meng Xingyu Zhang Qingxiong Liu Dr. Zhengyang Zhou Dr. Xingxing Jiang Prof. Yonggang Wang Prof. Zheshuai Lin Prof. Mingjun Xia 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2023,135(1):e202214848
Nonlinear optical (NLO) crystal, which simultaneously exhibits strong second-harmonic-generation (SHG) response and desired optical anisotropy, is a core optical material accessible to the modern optoelectronics. Accompanied by strong SHG effect in a NLO crystal, a contradictory problem of overlarge birefringence is ignored, leading to low frequency doubling efficiency and poor beam quality. Herein, a series of rare earth cyanurates RE5(C3N3O3)(OH)12 (RE=Y, Yb, Lu) were successfully characterized by 3D electron diffraction technique. Based on a “three birds with one stone” strategy, they enable the simultaneous fulfillment of strong SHG responses (2.5–4.2× KH2PO4), short UV cutoff (ca. 220 nm) and applicable birefringence (ca. 0.15 at 800 nm) by the introduction of rare earth coordination control of π-conjugated (C3N3O3)3− anions. These findings provide high-performance short-wavelength NLO materials and highlight the exploration of cyanurates as a new research area. 相似文献
108.
Yan-Jun Yu Chen Zou Wan-Shan Shen Xiaopeng Zheng Qi-Sheng Tian You-Jun Yu Chun-Hao Chen Baodan Zhao Prof. Zhao-Kui Wang Prof. Dawei Di Prof. Osman M. Bakr Prof. Liang-Sheng Liao 《Angewandte Chemie (International ed. in English)》2023,62(22):e202302005
Perovskite nanocrystals (PeNCs) deliver size- and composition-tunable luminescence of high efficiency and color purity in the visible range. However, attaining efficient electroluminescence (EL) in the near-infrared (NIR) region from PeNCs is challenging, limiting their potential applications. Here we demonstrate a highly efficient NIR light-emitting diode (LED) by doping ytterbium ions into a PeNCs host (Yb3+ : PeNCs), extending the EL wavelengths toward 1000 nm, which is achieved through a direct sensitization of Yb3+ ions by the PeNC host. Efficient quantum-cutting processes enable high photoluminescence quantum yields (PLQYs) of up to 126 % from the Yb3+ : PeNCs. Through halide-composition engineering and surface passivation to improve both PLQY and charge-transport balance, we demonstrate an efficient NIR LED with a peak external quantum efficiency of 7.7 % at a central wavelength of 990 nm, representing the most efficient perovskite-based LEDs with emission wavelengths beyond 850 nm. 相似文献
109.
Rapid chiral separation and impurity determination of levofloxacin by ligand-exchange chromatography
A sensitive, simple, and accurate method for determination of levofloxacin and its (R)-enantiomer was developed to determine the chiral impurity of levofloxacin in Cravit Tablets material by ligand-exchange high performance liquid chromatography. The effects of different kinds of ligands, concentration of ligands in mobile phase, organic modifier, pH of mobile phase, and temperature on enantioseparation were investigated and evaluated. Chiral separation was performed on a conventional C18 column, where the mobile phase consisted of a methanol-water solution (containing10 mmol L−1l-leucine and 5 mmol L−1 copper sulfate) (88:12, v/v) and its flow-rate was set at 1.0 mL min−1. The conventional C18 column offers baseline separation of two enantiomers with a resolution of 2.4 in less than 20 min. Thermodynamic data (ΔΔH and ΔΔS) obtained by Van’t Hoff plots revealed the chiral separation is an enthalpy-controlled process. The standard curves showed excellent linearity over the concentration range from 0.5 to 400 mg L−1 for levofloxacin and its (R)-enantiomer. The linear correlation equations are: y = 1.33 × 105x + 6297 (r = 0.9991) and y = 1.34 × 105x + 3565 (r = 0.9997), respectively. The relative standard deviation (RSD) of the method was below 2.3% (n = 3). 相似文献
110.
W.T. Lee E.K.H. Salje 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,13(2):395-398
Oscillatory zoning is a spatial variation in the composition of minerals. It has been observed in many different minerals
and a variety of mechanisms have been proposed to explain it. We propose an equilibrium model of oscillatory zoning in which
the variations in composition stabilise a ferroelastic phase. This results in a sinusoidal variation in composition. We expect
that this mechanism could account for oscillatory zoning found in minerals with oscillatory surface relaxations.
Received 9 March 1999 相似文献