电子-狄喇克双子束缚态的宇称性质及其斯塔克效应

讨论了电子—狄喇克双子束缚态解的宇称性质,指出:当q≠0(即磁荷存在)时,解的宇称确定性遭到破坏,因此破坏宇称守恒的△j=0的跃迁是允许的。从而产生了不同于通常类氢原子的线性斯塔克效应。还计算了该系统的斯塔克效应的能级分裂,指出了它不同于类氢原子的诸多特点。 关键词：     

Ar-HCl转动跃迁光谱线压力加宽截面的理论计算

本文利用量子力学的Infinite Order Sudden Approximation近似方法和Ar-HCl H6(2)相互作用解析势模型,计算了HCl分子转动跃迁谱线被Ar展宽的压力加宽截面（相对能量范围30cm^-1—1000^-1)和平均弛豫截面（系统温度125K,175K,300K）.通过与密耦合方法（CC）计算值及实验值的比较,发现IOSA近似方法对转动能级较为稀疏的分子的j=0←j=1转动路迁谱线仍然可给出较好的计算结果,但要用于转动激发态跃迁谱线的计 关键词：     

Ne-LiH体系势能面吸引阱对其散射动力学特征的影响

应用密耦方法,细致地讨论了Ne-LiH体系势能面的长程和高度各向异性的短程相互作用,对其非弹性散射动力学特征的影响.结果表明:①长程吸引和以排斥占优的短程相互作用在很窄的碰撞参数区域,相互竞争以至达到平衡,形成了暗度函数上明显的最小,并把势能面近似分隔为长程吸引和短程各向异性部分,②低Δj非弹性跃迁由这两部分共同作用产生,长程吸引势对Δj=1,2的跃迁有重要的贡献,特别对前者约占总截面的30%.而Δj≥3的跃迁则主要由短程的(排斥和吸引)相互作用决定.Ne原子从Li端以近共线方式接近LiH分子对产生Δj=1的跃迁最有利,以大于90°的Jacobi角接近则对较高Δj的跃迁有利.③较低Δj的微分截面集中在30°的质心散射角内,Δj=2~4呈现碰撞参数彩虹结构,Δj=6,7表现出转动彩虹的特征.长程吸引对Δj=1,2微分截面的贡献在10°散射角以内.对Δj=1的跃迁,势能的短程部分近似为纯排斥性的,而从Δj=2起,除短程排斥作用外,短程吸引部分的作用亦明显被反映.     

ZZd?137的荷电费密子-狄喇克双子束缚态的能谱结构

ZZ_d?137的荷电费密子-狄喇克双子束缚态的能谱,按照它们不同的K=n+[μ]_整数可以分为不同的线系,每个能级具有(2j+1)度简并。在均匀磁场中,由于塞曼效应,简并将完全消除。 关键词：     

Logistic系统跃迁率的时间延迟效应

本文研究了时间延迟对Logistic系统从亚稳态跃迁到稳定态的跃迁率的影响. 假设在细胞演化过程中细胞衰减存在时间延迟,利用小延迟时间条件下一阶近似方法和最陡下降法导出了系统的跃迁率解析式. 数值计算结果表明,内噪声,外噪声和内外噪声之间的关联促使系统从亚稳态跃迁到稳定态, 而时间延迟阻碍了系统从亚稳态到稳定态的跃迁, 即时间延迟增强了系统亚稳态的稳定性. 关键词： Logistic模型 跃迁率 时间延迟 噪声     

（Sr,Ba）Al12O19∶RE^3＋（RE=Ce,Tb）的VUV发光及Ce^3＋→Tb^3＋的能量传递

采用高温固相反应合成磁铅矿型(Sr,Ba)Al12O19∶RE3 (RE=Ce,Tb)发光材料,X射线衍射结果证明生成单一磁铅矿型结构。Ce3 产生302nm的发射峰和340nm左右的不太明显的肩,分别对应于5d→2F5/2和5d→2F7/2跃迁;激发光谱显示两个宽带峰,158nm峰对应于基质吸收,260 nm峰是由4f-5d跃迁引起的。Tb3 的发射光谱显示特征的5D3→7Fj(j=2,3,4,5)和5D4→7Fj(j=4,5,6)跃迁;在激发光谱中,160nm左右的峰是由基质吸收和Tb3 -O2-电荷迁移带交迭产生的,193nm峰是Tb3 的4f-5d自旋允许跃迁引起的,233nm弱的峰是自旋禁戒4f-5d跃迁产生的。Ce3 的发射和Tb3 的f-f跃迁吸收(~320 nm)完全交迭,并且Tb3 的发光强度随Ce3 的浓度增加而增强,从激发光谱看出,Tb3 发光部分来自于Ce3 的吸收,具有Ce3 →Tb3 能量传递。     

我的答复

潘登同志对我发表在本刊四卷一期上的文章提出了一些问题。现在,我就这些问题作一简要答复。 在我文章的第三节中首先证明了从n＇l＇能级到nlj能级自发发射跃迁几率正比于(2j 1),并对其它过程的跃迁几率进行了类似的讨论,指出在文章中所作的一定近似下,相同nl,不同j子壳层上的电子将按它们的统计权重(2j 1)的比例增加或减少;接着提出,同一     

He原子和BH分子碰撞体系的转动激发能量转移

在碰撞体系He+BH的CCSD(T)二维势能面基础上,应用密耦方法,研究了 He+BH分子碰撞转动激发过程.计算了该体系的转动态-态激发的弹性和非弹性的微分和积分截面,分析了计算结果与势能面特征间的关系.结果表明: He原子以从H原子端共线形式碰撞BH分子对j=0→j'=2的激发最为有效;短程排斥对Δj=2的激发作用较大;态-态跃迁总截面出现振荡结构,长程部分分波只对j=0→j'=1的跃迁总截面有较大贡献,j'≥ 关键词： He+BH体系 转动激发 散射截面     

布朗马达的非均匀高斯跃迁模型

提出了布朗马达的非均匀高斯跃迁理论，用布朗粒子在多态之间的跃迁模型描述分子马达的定向运动.假定跃迁速率与位置有关，且在跃迁点附近具有高斯函数形式，将布朗粒子在x处的概率密度Pm(x,t)在跃迁点附近展开，可以进行任意阶的近似计算.这一理论涵盖了以往的定点跃迁模型和均匀跃迁模型.作为具体例子，研究了系统在两态之间的跃迁问题.假定在一个周期内有两个跃迁点，讨论了布朗粒子定向运动产生的概率流随温度、跃迁速率和 跃迁宽度的变化关系. 关键词： 布朗马达 高斯跃迁 概率流     

量子混沌系统本征态的统计非遍历性及其半经典极限

讨论半经典极限下circular unitary ensemble(CUE)系综本征态θ_k(j)的非遍历性质.为研究量子系统本征态在统计上的非遍历性,定义了本征态分布ρ_k(j)的一对统计函数：Φ_N(j)=∑N-1k=0ρ_k(j)²和Ψ_N(j)=∑N-1k=0ρ_k(j),以分别体现量子本征态分布的凸起与凹陷.在随机矩阵理论的框架内,数值地计算了由正交归一的 关键词：     

三能级原子系统对光脉冲的响应及双光子三能级光子回波

分析了三能级原子系统对激光脉冲的响应。由此导出了双光子三能级光子回波形成条件。在实验上观察到这种新的光子回波,并用其测量了|3²D>+|3²P_3/2>Na和Ar的碰撞截面。 关键词：     

费密子与Dirac双子系统的耦合问题

除了库仑耦合和Kazama-杨振宁耦合——кqβ∑·r/2Mr³外,本文同时讨论了费密子Dirac双子应当存在的另一耦合iкzz_de²γ·r/2Mr³。结果表明,对所有角动量态,费密子径向波函数具有物理上合理的原点渐近行为。定性地分析了束缚态的必要条件。发现,对于双子情形,当额外磁矩к→0时,存在费密子束缚态是可能的;但对于磁单极情形,当к→0时,必不存在费密子束缚态。 关键词：     

面内场和静态偏磁场作用下条畴和泡畴的稳定性

实验研究面内场H_in和静态偏磁场H_b作用下,(111)面磁泡膜内条畴的消失过程。保持H_b恒定,增加H_in,测量条畴消失场H_s^*和泡畴消失场H_k^*与面内场方向β的变化关系。计及立方磁晶各向异性的影响,建立H_in和H_b共同存在时的条畴稳定性理论。定性解释了实验的主要特点。导出黑、白条畴同时消失时的角度 β_n=1/3(2nπ±arc cos│3/(2^1/2)(M_sH_b)/K₁│)(n=0,±1,±2,…)与实验基本符合。 关键词：     

Large dimensional lattice gauge theories: (I). Z2 pure gauge system

The transition pattern of lattice gauge theories can be stydied by a variational method based on strong coupling series. For large space-time dimension d, this leads to a 1/d expansion when the parameter βd is kept fixed. The first-order phase transition of the Z₂ pure gauge system is studied here.     

Asymptotic behavior of the density for two-particle annihilating exclusion

We consider a stochastic process which presents an evolution of particles of two types,A andB, onZ ^d with annihilations between particles of opposite types. Initially, at each site ofZ ^d, independently of the other sites, we put a particle with probability 2<1 and assign to it one of two types with equal chances. Each particle evolves onZ ^d in the following manner: independently from the others, it waits an exponential time with mean 1, chooses one of its neighboring sites on the latticeZ ^d with equal probabilities, and jumps to the site chosen. If the site to which a particle attempts to move is occupied by another particle of the same type, the jump is suppressed; if it is occupied by a particle of the opposite type, then both are annihilated and disappear from the system. The considered process may serve as a model for the chemical reactionA+Binert. Let (t) denote the density of particles in this process at timet. We prove that there exist absolute finite constantsc(d) andC(d) such that for all sufficiently larget,c(d)t ^–d/4 (t)C(d)t ^–d/4 in the dimensionsd4 andc(d)t ^–1 (t)C(d)t ^–1 in all higher dimensions. This completes and makes more precise the results obtained by us earlier and shows that asymptotically the density behaves like that in a similar process called two-particle annihilating random walks which was studied by Bramson and Lebowitz. Our proofs are based on the approach developed in their and our works. We use the basic properties of random walk and various tools which have been designed to study simple symmetric exclusion processes.     

Collective plasma corrections to thermonuclear reaction rates in dense plasmas

General kinetic equations are derived for nuclear reactions in dense plasmas by taking into account first-order collective plasma effects. We show that, apart from the corrections proportional to the product of the charges Z _i and Z _j of two reacting nuclei i and j, new corrections comparable in magnitude and proportional to the squares of the nuclear charges Z _i ² and Z _j ² arise. The Salpeter corrections [1] to the nuclear reaction probabilities due to the plasma screening of the interaction potential are shown to be at least a factor of r/d (r is the nuclear size and d is the Debye screening length) smaller than those assumed previously. These are zero in the approximation where the terms of order r/d are disregarded. The correlation corrections proportional to Z _iZ_j have a different physical meaning than those in [1], can have a different sign, and arise for reactions with zero Salpeter corrections. For the correlation corrections that substitute for the previously used Salpeter corrections, strong correlations are difficult to describe analytically. The interpolation formulas between weak and strong Salpeter screenings previously used in many astrophysical applications are inapplicable, because the interpolation formulas between weak and strong correlations cannot yet be obtained. We found a new type of corrections that are proportional to the squares of the charges of reacting nuclei. These are attributable to a change in the collective electrostatic self-energy of the plasma system during nuclear reactions. Plasma corrections for the hydrogen-cycle nuclear reactions are numerically calculated for the temperature, density, and abundances in the solar interior.     

On the Gibbs states for one-dimensional lattice Boson systems with a long-range interaction

We consider an infinite chain of interacting quantum (anharmonic) oscillators. The pair potential for the oscillators at lattice distanced is proportional to {d ²[log(d+1)]F(d)}^–1 where _rZ [rF(r)]^–1 < . We prove that for any value of the inverse temperature> 0 there exists a limiting Gibbs state which is translationally invariant and ergodic. Furthermore, it is analytic in a natural sense. This shows the absence of phase transitions in the systems under consideration for any value of the thermodynamic parameters.     

Color centers in the ionized and in the triplet state —Z 2 centers in ytterbium-doped KCl crystals

Z ₂ centers in Yb²⁺-doped KCl crystals are investigated by optical absorption experiments and by ESR experiments using the optically excited triplet state. Two mainZ ₂ center configurations have been found. One of them shows (100) axial symmetry and is optically orientable in the crystal. The other one possesses (110) symmetry elements. The measured fine structure constants are explained partly by dipole-dipole interaction of the two electronic magnetic moments partly by spin orbit interaction due to the Ytterbium impurity. The structure of the optical absorption spectra is attributed to as ²–s d charge transfer transition affected by the combined effect of crystal field and spin orbit interaction.     

类镍等电子系列离子M1,M2,E2禁戒跃迁特性的理论研究

利用基于全相对论框架下的多组态Dirac-Fock理论方法发展起来的程序包GRASP92和新发展的处理辐射跃迁过程的程序REOS99，计算了类镍等电子系列离子(Z=45—95)的基组态3s²3p⁶3d¹⁰¹S₀以及低激发组态3s²3p⁶3d⁹4l,3s²3p⁵3d¹⁰4l和3s3p⁶3d¹⁰4l(l=s,p,d,f)的能级及其向基态的M1,M2,E2禁戒跃迁概率.通过分析高离化类镍离子在特定的原子序数范围内由于存在能级交叉而产生的强组态相互作用，解释了高离化类镍离子禁戒跃迁概率的反常变化现象，探讨了禁戒跃迁概率受强组态相互作用影响而变化的一般规律.     

First-Order Phase Transition in Potts Models with Finite-Range Interactions

We consider the Q-state Potts model on Z ^d , Q≥ 3, d≥ 2, with Kac ferromagnetic interactions and scaling parameter γ. We prove the existence of a first order phase transition for large but finite potential ranges. More precisely we prove that for γ small enough there is a value of the temperature at which coexist Q+1 Gibbs states. The proof is obtained by a perturbation around mean-field using Pirogov-Sinai theory. The result is valid in particular for d = 2, Q = 3, in contrast with the case of nearest-neighbor interactions for which available results indicate a second order phase transition. Putting both results together provides an example of a system which undergoes a transition from second to first order phase transition by changing only the finite range of the interaction.