Effect of electron-phonon interaction on surface states in zinc-blende GaN,AlN, and InN under pressure

A variational approach is used to study the surface states of electrons in a semi-infinite polar semiconductor under hydrostatic pressure. The effective Hamiltonian and the surface-state levels are derived including the effects of electron-optical phonon interaction and pressure. The numerical computation has been performed for the surface-state energies versus pressure for zinc-blende GaN, AlN, and InN. The results show that the effect of electron-optical phonon interaction lowers the surface-state energy. It is also found that the effect of electron-surface optical phonon interaction is much bigger than the effect of electron-half space longitudinal optical phonon interaction for surface-state levels. It indicates that the surface-state energies and the influence of electron-phonon interaction increase with pressure obviously.Received: 12 June 2003, Published online: 22 September 2003PACS: 63.20.Kr Phonon electron and phonon-phonon interactions - 71.38.-k Polarons and electron-phonon interactions - 73.20.At Surface states, band structure, electron density of states     

Structure and side-chain interactions in poly(δ-N-carbobenzoxy L-ornithine)

Two crystal modifications are found in α-helical poly(δ-N-carbobenzoxy L -ornithine). In films as cast, the two-dimensional unit cell is pseudohexagonal and contains two chains. This form transforms irreversibly into a pseudotetragonal form at about 140°C. A second-order transition associated with the onset of the side-chain motion is observed at about 30°C for the bulk sample (by dilatometry) and for the crystalline phase (by x-ray diffraction). The dielectric behavior of the side-chain dispersion suggests that the side chains interact with one another. The temperature dependence of the infrared absorbance due to the NH stretching vibration reveals that about half the side chains are associated via hydrogen bonds at room temperature and become dissociated at higher temperature. The enthalpy and the entropy of the hydrogen bond formation is estimated to be ΔH = ?5.0 ± 0.5 kcal mol^?1 and ΔS = ?15 ± 1 e.u. mol^?1.     

Löslichkeit von Nickel-Zink-Ferriten in Säuren

Dissolution of zinc and nickel ferrites were previously found^2,3 to conform to the equations: $$\frac{{dx}}{{dt}} = ks_0 \left( {1 - x} \right)^3 K = \frac{1}{t}\left[ {\frac{1}{{\left( {1 - x} \right)^2 }} - 1} \right]$$ x-solubility (%),t=time (min),s ₀=initial specific surface (m ²·g^?1),k-rate constant independent of specific surface,K=apparent rate constant dependent on specific surface (min^?1). The aim of this work was to check the applicability of these equations to the dissolution of nickel—zinc ferrites. The experimental results obtained for 3 mixed ferrites (Ni_0.3Zn_0.7Fe₂O₄, Ni_0.5Zn_0.5Fe₂O₄, Ni_0.7Zn_0.3Fe₂O₄) revealed that kinetics of their dissolution in HCl, HNO₃ and their mixtures also conform to the equations stated above.     

非周期保守动力系统的自统计规律性

本文详细研究了一个典型的非线性、非周期保守动力系统——无阻尼、无碰撞耗散的掷硬币过程,着重考察了该过程的久期规律性,发现这个由给定初始条件确定的决定性过程,在长时间中显现出明确的“自统计规律性”。本文还计算了该过程的Poincaré回复周期及其对回复精度的依赖性。     

Löslichkeit von Nickelferrit in Säuren

The kinetics of the dissolution of nickel ferrite in acids (HCl, HNO₃) was studied. The kinetic equation of the \(\frac{{dx}}{{dt}} = s_0 k (1 - x)^3\) type was derived on the base of the experimental results obtained, and the dissolution rate constantsK andk are calculated.     

薄层色谱溶剂系统的最优化方法的研究第Ⅷ报外部惩罚函数法

以１０种已知磺胺的混合物为例，采用外部惩罚函数法在计算机上处理数据，对其薄层色谱溶剂系统进行优化，优化的结果为甲苯：无水乙醇；１，２－二氯乙烷：三氯甲烷＝０．６８：０．７８：４．１３：４．４１，分离结果比较满意，是一种比较有效的系统化方法。