ATOMIC CHARGE SUPERPOSITION CALCULATIONS OF STM IMAGES OF 2D-ORDERED AMINO ACID ADSORBATES(Ⅰ)

In a previous STM investigation by Yang and co-workers a variety of 2D ordered atomic-scale features of glycine molecules adsorbed on graphite were observed and several models have been proposed to interpret these features. In the present work, atomic charge superposition(ACS) calculations of STM images of their models were carried out. The calculated images match the experimental ones fairly well, indicating the general validity of the ACS method to the glycine/graphite system and the correctness of their interpretations. The reason of the validity, the origin of the atomic resolution, and the proper tip-sample distance are also discussed.     

ATOMIC CHARGE SUPERPOSITION CALCULATIONS OF STM IMAGES OF 2D-ORDERED AMINO ACID ADSORBATES(Ⅱ)

In the preceding paper, we have successfully used the atomic charge superposition (ACS) method to calculate STM images of 2D-ordered structures of glycine molecules adsorbed on graphite (HOPG). In this work we focus on alanine/HOPG system. Firstly, we make a thorough searching for all of the possible 2D-ordered aggregation structures that can form linear chains or 2D nets of hydrogen bonds between the molecules and simultaneously satisfy the Van der Waal's radii of the condtituent atoms, just like in the case of 3D crystal of the molecules. Secondly, in order to interpret the experimental images, we use the ACS method to calculate STM images of the possible structures. It turns out that many of the experimental images can be interpreted satisfactorily with their calculated counterparts. This result further exhibits the great potential of using STM to study organic and biological molecules.     

ON THE PROBLEM OF THE DUAL CHARGE (MAGNETIC MONOPOLE) OF NON-ABELLAN GROUPS (Ⅱ)

The method of relating the gauge potential to the connection on a spherical surface developed in a previous paper is generalized to the discussion of the potential of an SU(2) magnetic monopole with O(5) symmetry. Expressions for the potential of the monopole with double string singularity or single string singularity are obtained. Finally, by a combined coordinate-gauge transformation, we obtain a string free expression for an SU(2) magnetic monopole with O(5) symmetry.     

RELATIVISTIC SEMICLASSICAL THEORY OF CONDENSATION (Ⅰ)

Exact relations between the energy of a symmetric nuclear matter loaded in a classical π field and the value φ and wave number k of this π field were obtained for pseudoscalar coupling and pseudovector coupling. Results show that there is no π condensation under pseudoscalar coupling. If pseudovector coupling (which is not renormalizable) were permitted, π condensation emerges as a result of π nucleon P wave interaction, and the chiral symmetry is not necessary. π nucleon interaction itself leads to saturation of the condensed π field. Nonlinear selfinteractions of π field, such as φ⁴ term and so on, are not necessary. The influence of nucleonic repulsive core were considered under Yan der Waals approximation. It leads to upper and lower limits on wave numbers of the condensed π fields. If the radius of the repulsive core were larger than a critical value, π condesation becomes impossible again.     

EFFECT OF ATOMIC HYDROGEN ON THE ACETYLENE-ADSORBED Si(100)(2×1) SURFACE AT ROOM TEMPERATURE

High resolution electron energy loss spectroscopy, low energy electron diffraction and quadrupole maas spectrometer (QMS) have been employed to study the effect of atomic hydrogen on the acetylene-saturated pre-adsorbed Si(100)(2×1) surface and the surface phase transition at room temperature. It is evident that the atomic hydrogen has a strong effect on the adsorbed C₂H₂ and the underlying surface structure of Si. The experimental results show that CH and CH₂ radicals co-exist on the Si surface after the dosing of atomic hydrogen; meanwhile, the surface structure changes from Si(100)(2×1) to a dominant of (1×1). These results indicate that the atomic hydrogen can open C=C double bonds and change them into C-C single bonds, transfer the adsorbed C₂H₂ to C₂H_x(x = 3,4) and break the underlying Si-Si dimer, but it cannot break the C-C bond intensively. The QMS results show that some C₄ species axe formed during the dosing of atomic hydrogen. It may be the result of atomic hydrogen abstraction from C₂H_x which leads to carbon catenation between two adjacent C-C directs. The C₄ species formed are stable on Si(100) surfaces up to 1100 K, and can be regarded as the potential host of diamond nucleation.     

EFFECT OF ATOMIC HYDROGEN ON THE ACETYLENE-ADSORBED Si(100)(2×1) SURFACE AT ROOM TEMPERATURE

High resolution electron energy loss spectroscopy, low energy electron diffraction and quadrupole maas spectrometer (QMS) have been employed to study the effect of atomic hydrogen on the acetylene-saturated pre-adsorbed Si(100)(2×1) surface and the surface phase transition at room temperature. It is evident that the atomic hydrogen has a strong effect on the adsorbed C₂H₂ and the underlying surface structure of Si. The experimental results show that CH and CH₂ radicals co-exist on the Si surface after the dosing of atomic hydrogen; meanwhile, the surface structure changes from Si(100)(2×1) to a dominant of (1×1). These results indicate that the atomic hydrogen can open C=C double bonds and change them into C-C single bonds, transfer the adsorbed C₂H₂ to C₂H_x(x = 3,4) and break the underlying Si-Si dimer, but it cannot break the C-C bond intensively. The QMS results show that some C₄ species axe formed during the dosing of atomic hydrogen. It may be the result of atomic hydrogen abstraction from C₂H_x which leads to carbon catenation between two adjacent C-C directs. The C₄ species formed are stable on Si(100) surfaces up to 1100 K, and can be regarded as the potential host of diamond nucleation.     

STATICAL SPHEROSYMMETRICAL SOURCELESS SOLUTION OF SU(2) GAUGE FIELD——THE SELFDUALITY,UNIQUENESS AND THE SELF INDUCED CHARGE CURRENT

It is shown that the statical spherosymmetrical sourceless solutions of SU(2) guagefield,which satisfy a physical boundary condition,must be selfdual.Then from theselfdual condition,we solve the equation explicitily,hence show the uniqueness analy-tically.By gauge transforming the Lagrangian by a local generator of synchrono-symmetry,we get a corresponding local charge current density,which is both gaugeinvariant and conserved.The total values of either electric or magnetic charge arequantized,but the charge distributions in space are continuous and not restrictedby quantization.Finally we discuss a mechanism of spontaneous symmetry break-down.Contrary to ordinary magnetic flux string,now the ordered phase is surround-ed by the normal phase,the ordered phase repels electric fields,and electric fieldsdestory the ordered phase.     

FINE STRUCTURES OF INCLUSIVE SPECTRA(Ⅰ)——SUM RULES AND THE GENERALIZATION OF FEYNMAN-YANG SCALING

Important implications of the fine structure of inclusive spectra(to be calledinclusive and semi-inclusive spectra of nearby particles,which represent the local dis-tributions of nearby particles in three-dimensional phase space with rapidity y and transverse momenta P_⊥x, P_⊥z as independent coordinates are explained,and some basicfeatures of the fine stucture are found,namely,sum rules and the generalized formof the Feynman-Yang scaling.One of the sum rules,for example,is:where f_(1;k) denotes the normalized invariant inclusive cross section of k closely neigh-boring particles.It follows that the inclusive the spectra of nearby particles arequalitatively different from the usual ones.The generalized form of the Feynman-Yang scaling for the case of k closelyneighboring particles,for example,is:f_(1;k)(s,x₁,P_⊥1,…x_k,P_⊥k⁾∞,（s→∞,x₁≤x₂≤…≤x_k）.where‘∞’denotes‘approaches a definite limit’.For k=2,the existing experimentaldata for the rapidity gap-length distributions show that for FNAL energies,f_(1,k） isalready close to its limiting form.The inclusive（semi-inclusive）spectra of nearbyparticles way be able to reflect effectively short-range correlation effects.     

STM study of Pd growth on TiO2(100)-(1 × 3)

STM has been used to study the initial growth of palladium on TiO₂(100)-(1 × 3). The results demonstrate that STM is capable of imaging individual atoms which form part of a supported metal cluster. The data were obtained from small (35Ådiameter by 8Åhigh) clusters at a dispersed-equivalent coverage of about 0.01 ML. At higher coverages the clusters coalesce.     

RECENT PROGRESS OF(e,2e) SPECTROSCOPY

Recent progress of(e,2e)spectroscopy,or Electron Momentum Spectros-copy(EMS),on laser excited oriented atoms,large bio-organic moleculesand thin films is reviewed.     

THE ANALYSIS OF RADIOACTIVE DECAY CURVES (Ⅰ) TWO-COMPONENT DECAY CURVES——INTRODUCTION OF A NON-CLASSICAL METHOD OF ANALYSIS

In present paper, a non-classical method ("λ" method) of analyzing the two-component radioactive decay curve was developed. The use of the relationship between the apparent decay constant λ(t) and the time t in fitting is to be distinguished from the use of the relationship between the total activity A(t) and t in fitting by the classical method ("A" method). In "λ" method, there are three unknowns while in "A" method there are four, thus the former is simpler than the latter.     

c(2×2)O吸附Cu(001)表面结构、电子态与STM图像的研究

用投影子缀加波和CP分子动力学方法研究了贵金属Cu(001)面的表面结构、弛豫以及O原子的c(2×2)吸附状态. 研究结果得出在这种吸附结构中，O原子与衬底Cu原子之间的垂 直距离约为0069nm，Cu—O键长为0.194nm，功函数约为5.29 eV；吸附O原子形成金属性能带结构，由于Cu—O的杂化作用,在费米能以下约6.7 eV处出现了局域的表面态.用Tersoff-Hamann途径计算了该表面的扫描隧道显微镜图像，并讨论了与实验结果之 间的关系. 关键词： Cu(001)-c(2×2)/O 电子态 STM图像     

THEORY OF SOLITON GENERATION AND LATTICE RELAXATION IN POLYACETYLENE (Ⅰ) GENERAL FORMALISM

This series of papers is devoted to the theory of soliton and polaron generation in polyacetylene by both radiative and non-radiative processes. In the first paper of this series a general formalism is presented which combines the Lattice relaxation approach for the multiphonon process developed by Huang and many others with the consistency condition in terms of the Bogoliubov-de Gennes equation and the gap equation. The exact adiabatic electron wave functions consistent with the different lattice syimnetry breaking in the initial and final states are used to calculate the transition probability between these multi-electron states. The formalism presented is illustrated by deriving a general expression for the non-radiative decay rate using the steepest descent method in the case of stronc coupling. The theory developed here canbe applied to treating the quantum. transitions between states of differnet symmetry breaking when the multi-electron background effect and the consistency condition are essential.The applications of the general formalism to polyacettyene and the comparison with numerical results and the recent experiments tvi11 be given in the succeeding papers.     

THE FLUID THEORY OF SELF-SUSTAINING MAGNETICALLY CONFINED ELECTRON CLOUDS (Ⅰ) FLUID EQUATIONS

In this paper the axisymmetrical self-sustaining magnetically confined electron clouds are studied by means of the fluid theory.In the electron clouds which supported by the Penning discharge the property of motion of electrons can be described by the fluid equations:continuity equation,momentum equation,energy equation,Poisson equation and heat transfer equation.The problems of the diffusion and escape of electrons and the energy transport in the electron clouds are discussed.     

金红石型TiO2(110)表面性质及STM形貌模拟

采用密度泛函理论从头计算了金红石型TiO2(110)表面的相关性质,切片模型含有9层原子,采用化学整比表面结构,晶胞真空层厚度为1.5nm,原子价电子采用超软赝势表达.差分电子密度分布图发现原子附近区域电子密度分布以球对称为主,电子定域形成离子键的趋势较强,但在Ti和O原子之间存在较弱的共价键.模拟了金红石型TiO2(110)表面结构的扫描隧道显微镜(scanning tunneling microscope,简称STM)图像,利用Tersoff-Hamann的成像理论,在 2 V的正向偏压下,采用一系列变化的数值作为STM探针离表面桥式氧的距离,分析了相关态密度的变化,发现(110)表面的STM形貌凸起部分来自于5-Ti原子,而不是2-O原子(桥式氧),在TiO2(110)表面结构成像中,电子效应起主导作用,证实了STM实验观察到的亮行是Ti原子的结果.     

离子溅射(Ⅰ)

荷能粒子轰击固体表面,打出离子和中性原子的现象称为溅射．由于离子易于在电磁场中加速或偏转,所以荷能粒子一般为离子,称这种溅射为离子溅射．随着真空技术、薄膜技术、表面分析技术以及表面科学的发展。离子溅射的用途越来越广泛,其重要性也日益为人们所共知．如今,离子溅射在溅射离子源、二次离子质谱分析（ＳＩＭＳ）、离子束分析、溅射镀膜、离子镀、离子和离子束刻蚀、表面微细加工等领域有广泛的应用．同时,溅射?...     

LIE THEOREM VIA RANK 2 DISTRIBUTIONS (INTEGRATION OF PDE OF CLASS ω = 1)

In this paper we investigate compatible overdetermined systems of PDEs on the plane with one common characteristic. Lie's theorem states that its integration is equivalent to a system of ODEs, and we give a new proof by relating it to the geometry of rank 2 distributions. We find a criterion for integration in quadratures and in closed form, and discuss nonlinear Laplace transformations and symmetric PDE models.