Sixfold symmetry of excitonic transition energies in c-plane for wurtzite GaN

The optical properties of the strained wurtzite GaN are investigated theoretically within the nearest neighbor tight-binding method. The piezoelectric effect is also taken into account. The empirical rule has been used in the strained band-structure calculation. The results show that the excitonic transition energies are anisotropic in the c-plane in a high electronic concentration system and have a 60 degrees periodicity, which is in agreement with experiment. (C) 2008 American Institute of Physics. [DOI: 10.1063/1.3001937]

Investigation of Electronic Energy Levels in InAs Quantum Dot with Shape of Lens by Using B-Spline Technique

The dependence of the electronic energy levels on the size of quantum dots (QDs) with the shape of spherical lens is studied by using the B-spline technique for the first time. Within the framework of the effective-mass theory, the values of electronic energy levels are obtained as a function of the height, radius and volume of QDs, respectively. When the height or radius of QDs increases, all the electronic energy levels lower, and the separations between the energy levels decrease. For lens-shape QDs, height is the key factor in dominating the energy levels comparing with the effect of radius, especially in dominating the ground-state level. These computational results are compared with that of other theoretical calculation ways. The B-spline technique is proved to be an effective way in calculating the electronic structure in QDs with the shape of spherical lens.

Computer simulation of a-Si : H/mu c-Si : H diphasic silicon solar cells

Based on our experimental research on diphasic silicon films, the parameters such as absorption coefficient, mobility lifetime product and bandgap were estimated by means of effective-medium theory. And then computer simulation of a-Si: H/mu c-Si: H diphasic thin film solar cells was performed. It was shown that the more crystalline fraction in the diphasic silicon films, the higher short circuit density, the lower open-circuit voltage and the lower efficiency. From the spectral response, we can see that the response in long wave region was improved significantly with increasing crystalline fraction in the silicon films. Taking Lambertian back refraction into account, the diphasic silicon films with 40%-50% crystalline fraction was considered to be the best intrinsic layer for the bottom solar cell in micromorph tandem.

Anisotropic strain relaxation of thin Fe film on c(4 x 4) reconstructed GaAs (001) surface

National Natural Science Foundation of China 60836002 10674130 60521001;Major State Basic Research of China 2007CB924903;Chinese Academy of Sciences KJCX2.YW.W09-1

The effects of nonlinear couplings and external magnetic field on the thermal entanglement in a two-spin-qutrit system

We investigate the effects of nonlinear couplings and external magnetic field on the thermal entanglement in a two-spin-qutrit system by applying the concept of negativity. It is found that the nonlinear couplings favor the thermal entanglement creating. Only when the nonlinear couplings vertical bar K vertical bar are larger than a certain critical value does the entanglement exist. The dependence of the thermal entanglement in this system on the magnetic field and temperature is also presented. The critical magnetic field increases with the increasing nonlinear couplings constant vertical bar K vertical bar. And for a fixed nonlinear couplings constant, the critical temperature is independent of the magnetic field B. (c) 2005 Elsevier B.V. All rights reserved.

Effect of dead carbon on the C-14 dating of the speleothem

IEECAS SKLLQG

Rotation and deformation of the dinuclear system formed in dissipative reaction of F-19+Al-27

Excitation functions of the reaction products B, C, N, O, F and Ne emitted from the dissipative reaction of (19) F+(27) Al have been measured at incident energies from 110.25MeV to 118.75MeV in steps of 250keV. The moments of inertia of the intermediate dinuclear system formed in the reaction are extracted from the energy autocorrelation functions of the products. Comparing the moment of inertia extracted from the experimental data with the calculated one by using the sticking limit, it indicates that the formed dinuclear system has a large deformation in the reaction process.

Restudy on the wave functions of Gamma(nS) states in the light-front quark model and the radiative decays of Gamma(nS) -> eta(b) + gamma

The light-front quark model has been applied to calculate the transition matrix elements of heavy hadron decays. However, it is noted that using the traditional wave functions of the light-front quark model given in the literature, the theoretically determined decay constants of the Gamma(nS) obviously contradict the data. This implies that the wave functions must be modified. Keeping the orthogonality among the nS states and fitting their decay constants, we obtain a series of the wave functions for Gamma(nS). Based on these wave functions and by analogy with the hydrogen atom, we suggest a modified analytical form for the Gamma(nS) wave functions. Using the modified wave functions, the obtained decay constants are close to the experimental data. Then we calculate the rates of radiative decays of Gamma(nS) -> eta(b) + gamma. Our predictions are consistent with the experimental data on decays Gamma(3S) -> eta(b) + gamma within the theoretical and experimental errors.

~(12)C与~(209)Bi反应中Au同位素的产额与Q_(gg)的关系；Q_(gg)-Yield Dependence of Au Isotopes in Interaction of 47 MeV/u ~(12)C With ~(209)Bi

用47MeV/u12C离子轰击天然铋靶,通过炮弹和靶核之间的核子转移反应产生Au同位素。使用放射化学方法从大量Bi和复杂反应产物中分离、纯化Au,并制备Au的γ射线测量源。使用HPGe探测器测量放射性Au同位素的γ活性。根据照射结束时Au同位素的活度和其他相关数据,确定每个Au同位素的产生截面。分析发现,缺中子Au同位素的产生截面与Qgg值之间不遵从指数依赖关系,这可用重离子碰撞中的次级过程加以解释。

~(12)C离子束辐照对酵母发酵能力的影响；Improved ethanol fermentation of a yeast mutant by C-12 ion beam irradiation

利用100MeV/u的12C6+离子束辐照酵母Saccharomyces cerevsiea YY,选育出一株高产突变菌株C03A,考察C03A发酵过程中不同温度、pH、糖汁浓度对发酵的影响。通过正交实验确定最佳发酵条件为:糖汁浓度24%、温度35℃、pH5.0。在10L发酵罐实验中,C03A发酵速率相对原始菌株高,36h发酵完全,比原始菌株缩短12h;发酵产酒率达到13.2%(V/V),比原始菌株高1.6%(V/V)。

Crystallization and morphology of poly(ethylene oxide-b-lactide) crystalline-crystalline diblock copolymers

The crystallization behaviors and morphology of asymmetric crystalline-crystalline diblock copolymers poly(ethylene oxide-lactide) (PEO-b-PLLA) were investigated using differential scanning calorimetry (DSC), wide angle X-ray diffraction (WAXD), and microscopic techniques (polarized optical microscopy (POM) and atomic force microscopy (AFM)). Both blocks of PEO5-b-PLLA(16) can be crystallized, which was confirmed by WAXD, while PEO block in PEO5-b-PLLA(30) is difficult to crystallize because of the confinement induced by the high glass transition temperature and crystallization of PLLA block with the microphase separation of the block copolymer.

Molecular weight dependence of phase Behavior of PEO/P(EO-b-DMS) blends: Application of Sanchez-Lacombe lattice fluid theory

Molecular weight dependence of phase separation behavior of the Poly (ethylene oxide) (PEO)/Poly(ethylene oxide-block-dimethylsiloxane) (P(EO-b-DMS)) blends was investigated by both experimental and theoretical methods. The cloud point curves of PEO/P(EO-b-DMS) blends were obtained by turbidity method. Based on Sanchez-Lacombe lattice fluid theory (SLLFT), the adjustable parameter, epsilon*(12)/k (quantifying the interaction energy between different components), was evaluated by fitting the experimental data in phase diagrams. To calculate the spinodals, binodals, and the volume changes of mixing for these blends, three modified combining rules of the scaling parameters for the block copolymer were introduced.