声表面波对GaAs(110)量子阱发光特性的调制

结合声表面波和光致发光谱在低温(15K)下对非故意掺杂的GaAs(110)量子阱结构的发光特性进行了研究.实验结果表明，由于声表面波的作用GaAs(110)量子阱的发光强度减弱,并且其对应的重空穴能级出现了分裂的现象，当施加的声波强度P_rf达到20dBm时，能级分裂ΔE达到了10meV.进一步讨论了声表面波对GaAs(110)量子阱圆偏振光自旋注入的影响. 关键词： 发光 GaAs量子阱 声表面波 自旋极化     

Magnetic properties of the Cr(0 0 1) surface studied by spin-polarized scanning tunneling spectroscopy

The magnetic properties of the Cr(0 0 1) surface have been studied by spin-polarized scanning tunneling spectroscopy (SP-STS). Spatially resolved mapping of the spectroscopic dI/dU signal at an energy close to the spin-polarized Cr(0 0 1) surface state allows the confirmation of the topological antiferromagnetic order of the Cr(0 0 1) surface. It is shown that the presence of screw dislocations leads to the formation of domain walls which exhibit a width of 120–170 nm. A long-period modulation of the SP-STS signal was not observed indicating that the bulk spin-density wave is modified at the surface due to symmetry breaking.     

Quintessence and Dark Matter Created by Weyl–Dirac Geometry

A spatially closed universe undergoing at present accelerated expansion, having a non-vanishing cosmological constant, and filled with luminous- and dark matter is described in terms of the Integrable Weyl–Dirac theory. It is shown that, during the dust-dominated period, dark matter and the quintessence pressure, the latter giving rise to acceleration: both are created by the Dirac gauge function. The behavior of two models: a nearly flat one and a well closed are considered in appropriate gauges, and plausible scenarios are obtained. The outcome of the present paper, together with results of a previous work,⁽³¹⁾ provide a geometrically based, classical, singularity-free model of the universe, that has originated from a pure geometric Weyl–Dirac entity, passed a prematter period, the radiation-dominated era, and continues its development in the present dust period.     

Numerical Soliton and Oscillating Wave Solutions for Flierl-Petviashvili Equation in Plasmas

Numerical axisymmetric soliton and oscillating wave solutions for the Flierl-Petviashvili equation in plasmas are presented. Solution branch paradigm and examples are given. Some implications of results to ion drift wave as well as force-free field of magnetic equilibrium are briefly discussed.     

Averaged topological equations for dispersed two-phase flows

A general relationship between the volume fraction and the specific interfacial area for averaged dispersed two-phase flows is proposed. This relationship, expressed as a basic set of two scalar evolution equations and two vectorial non-uniformity state equations, is an analytical result obtained by a systematic approach using the derivatives of some generalized functions and a local volume-averaging technique. The proposed set of equations was expressed for measurable macroscopic parameters of the system and has the same generality as the averaged transport equations of two-phase flows. By combination of the basic set of equations, called the averaged topological equations (ATEs), second-order ATEs for the volume fraction were found. The second-order ATEs were expressed both by a Lagrangian formulation and by a Eulerian formulation. The importance and physical meaning of the ATEs developed in this study were clarified within the framework of the theory of kinematic waves.     

中能区光学势的温度效应

本文在Skyr}e相互作用、核物质近似和自洽半经典方法的基础上，将微观光学势的自洽研究推J“到中能区(60-r300MeV)，研究了”+907r在该能区光学势的径向形状和温度效应     

Nitrated polynuclear aromatic hydrocarbons in ambient air in Italy. A brief overview

When nitrated polynuclear aromatic hydrocarbons (NPAH) were recognised as long‐term toxic compounds and were also identified in several anthropogenic emissions and among the by‐products of photochemical smog they became objects of investigation in ambient air in both polluted and clean environments. In Italy the first investigations focussing on atmospheric NPAH were performed in the early eighties and encompassed both the canyon streets and dwelling areas of Rome. Because NPAH were indicated as markers of vehicle emission, new investigations were performed in other cities and also in rural and (nominally) unpolluted locations. In general, the first measurements of NPAH were episodic and could not be assumed to be strictly representative of the sites investigated. In contrast, nowadays consistent data bases on NPAH have been built up and are discussed in the technical literature, so that both neat concentrations and the yearly timed variation of the most important NPAH congeners have been measured in Italian air. Although concentrations of NPAH in air are usually much lower than those of PAH, owing to their very high potency in inducing mutations and tumours NPAH are regarded as having an important health impact on populations living in Italian urban areas. In this regard the genotoxicity of atmospheric aerosols is partly associated with nitrofluoranthenes and nitropyrenes whereas nitronaphthalenes and methylnitronaphthalenes seem to contribute to that of the gaseous organic fraction. Several civic and regional administrations are introducing control of atmospheric NPAH among ways of improving air quality in cities.     

Resonant Raman scattering from a spin density wave insulator

We present a calculation of the electronic Raman cross section for the scattering of light across the energy gap of an antiferromagnetic insulator. The antiferromagnet is described in terms of a spin density wave state for the Hubbard model at half filling. We consider the coupling of the light to the current density and the inverse mass tensor on equal footing. A comparison of the cross section for different scattering geometries is given.     

颗粒物质的两个典型效应及其研究现状的分析

概述了颗粒物质领域中粮仓现象和巴西坚果效应两个典型现象及其解释理论，分析其理论的成功和不足之处，并给出了一些看法。     

微观世界探索

论文系统地阐述了从原子、原子核到基本粒子内部结构研究的历史及现状，讨论了微观物理理论和实验研究的前景和展望．论文还阐述了微观物理与宏观物理(宇宙论和天体物理等)的结合与交叉，以无可争辨的实验事实阐明了微观世界和宏观世界的无限性．