Pockels介质平板中的光波传输

本文讨论了非线性对称平板波导中的TE波的偶模及奇模的传输问题.平板波导的芯区材料是由Pockels介质所构成,包层与衬底是相同的线性材料.Pockels介质的介电系数为ε=n²+α|E|,故问题归结为求解芯区的传输方程.本文给出了芯区、包层及衬底中光波的解析解以及传播常量β的本征值方程等.     

里兹方法在光波导理论中的应用

本文讨论了在三层平板介质波导中TE波的传播问题.三层平板的芯区由Kerr介质构成,其折射率平方(n²)的剖面分布随x作抛物分布变化.本文将应用变分法中的里兹方法,求出亥姆霍兹方程的第一级近似的解析解.     

Hulthén势散射态的解析解

在任意l波的离心项1/r²用λ²e^-λr/(1-e^-λr)²近似表达的条件下,对Hulthén势的径向Schrdinger方程作自变量指数变换,使此转化为超几何微分方程,获得了Hulthén势s波散射态的精确解和非s波散射态的近似解析解.给出了相移的解析表达式和按“k/2π标度”归一化的用超几何函数表示的径向波函数.讨论了解析解的意义.     

Spectroscopic investigations on NO+(x1∑+,a3∑+,A1Ⅱ) ion using multi-reference configuration interaction method and correlation-consistent sextuple b

Three low-lying electronic states (x¹∑⁺,a³∑⁺,and A¹Ⅱ) of NO⁺ ion are studied using the complete active space self-consistent-field (CASSCF) method followed by highly accurate valence internally contracted multi-reference configuration interaction (MRCI) approach in combination of the correlation-consistent sextuple basis set augmented with diffuse functions, aug-cc-pV6Z. The potential energy curves (PECs) of the NO⁺(x¹∑⁺,a³∑⁺,A¹Ⅱ) are calculated. Based on the PECs, the spectroscopic parameters R_e, D_e, ω_e, ω_eχ_e, α _e, B_e, and D₀ are reproduced, which are in excellent agreement with the available measurements. By numerically solving the radial Schrödinger equation of nuclear motion using the Numerov method, the first 20 vibrational levels, inertial rotation and centrifugal distortion constants of NO⁺(x¹∑⁺,a³∑⁺,A¹Ⅱ) ion are derived when the rotational quantum number J is equal to zero (J = 0) for the first time, which accord well with the available measurements. Finally, the analytical potential energy functions of these states are fitted, which are used to accurately derive the first 20 classical turning points when J = 0. These results are compared in detail with those of previous investigations reported in the literature.     

激发对相干态的等阶Y压缩效应

用数值计算法研究了激发对相干态|ζ;m〉＝a^+mb^+m|ζ〉的等阶Y压缩效应.结果表明:对于态a^+mb^+m|ζ〉,光场存在着等阶K(＝2,3,4,5,…)次方Y压缩效应,但是随着场模上光子增加数m的增大,等阶K次方Y压缩效应减弱.     

boldmath B3Σu-–X3Σg- transition in selenium dimer: ab initio multireference configuration interaction calculations

Theoretical investigation of low-lying electronic states and B³Σ_u^-–X³Σ_g^- transition properties of selenium dimer using size-extensivity singly and doubly excitation multireference configuration interaction theory with nonrelativistic all-electron basis set and relativistic effective core potential plus its split valence basis set is presented in this paper. The spectroscopic constants of ten low-lying Λ-S bound states have been obtained and compared with experiments. Spin-orbit calculations for coupling between B³Σ_u^- sates and repulsive ¹Π_u, ⁵Π_u states have been made to interpret the predissociation mechanisms of the B³Σ_u^- state. The lifetimes of B³Σ_u^- (v=0～6) have been calculated with scalar relativistic effects included or excluded, respectively, and reasonably agree with experimental values.     

氮原子在800 nm附近的同位素位移

The Doppler-limited absorption spectra of ¹⁴N and ¹⁵N atoms were measured around 800 nm using concentration modulation spectroscopy to study their isotope shifts. The nitrogen atoms were generated by discharging molecular nitrogen buffered with helium in a homemade discharge tube. The isotope shifts of four multiplets (3s⁴P_J→3p⁴D_J^o, 3s⁴P_J→3p⁴P_J^o, 3s²D_J→5s²P_J^o, and 3p²P_J^o→5s²D_J^o) were measured and their J-dependent specific mass shifts were observed and discussed.     

199Hg+光频标的黑体辐射频移

光学频率标准会受到环境温度的黑体辐射影响发生频移,进而影响其准确度. 本文估算了¹⁹⁹Hg⁺的超精细能级5d¹⁰6s²S_1/2 (F=0)和5d⁹6s^{2 2}D_5/2 (F=2)的极化率,得到了室温(300 K)下黑体辐射引起的相对频移为-5.4×10^-17, 最后讨论了低温环境下黑体辐射对¹⁹⁹Hg⁺光频标的影响.     

Calculation of O(p6) corrections to the muon transverse polarization in Kl2γ decay

The contribution of final-state interactions to the muon transverse polarization in the decay K ⁺ → μ⁺ v γ is calculated within chiral perturbation theory to O(p ⁶) terms. It is shown that the O(p ⁶) corrections to the transverse polarization are much smaller than the O(p ⁴) leading contribution. Original Russian Text ? V.V. Braguta, A.A. Likhoded, A.E. Chalov, 2007, published in Yadernaya Fizika, 2007, Vol. 70, No. 2, pp. 386–391.     

ErP5O14非晶玻璃的红外量子剪裁

研究了Er_1.0P₅O₁₄铒非晶玻璃的红外量子剪裁现象. 从吸收谱和激发光谱的计算比较中肯定了Er_1.0P₅O₁₄非晶 玻璃的1537.0 nm红外荧光为多光子量子剪裁荧光. 从Er_1.0P₅O₁₄非晶玻璃的可见和红外荧光发射光谱中发现激发²H_11/2, ⁴G_11/2和⁴G_9/2能级所导致的⁴I_13/2→⁴I_15/2量子剪裁红外荧光很强;基于自发辐射速率、无辐射弛豫速率和能量传递速率等参数的计算,对其量子剪裁机理进行了分析.发现起源于基态的强下转换能量传递{²H_11/2→⁴I_9/2,⁴I_15/2→⁴I_13/2},{⁴G_11/2→⁴I_13/2, ⁴I_15/2→²H_11/2},{⁴G_9/2→⁴F_7/2,⁴I_15/2→⁴I_13/2}和{⁴G_9/2→⁴I_13/2, ⁴I_15/2→²H_11/2}是导致Er_1.0P₅O₁₄非晶玻璃具有强的三光子和四光子量子剪裁红外荧光的原因.研究结果对改善太阳能电池效率有一定意义.     

FeCo基磁芯螺线管巨磁阻抗效应与磁芯长度关系的研究

研究了Fe₃₆Co₃₆Nb₄Si_4.8B_19.2合金薄带为磁芯的螺线管(FeCo基磁芯螺线管)的巨磁阻抗效应与磁芯长度之间的关系.研究结果表明,磁芯长度是影响FeCo基磁芯螺线管巨磁阻抗效应的重要因素.当磁芯长度小于螺线管长度时,磁芯螺线管巨磁阻抗的最大值(ΔZ/Z)_max与磁芯长度呈线性关系,其线性相关系数可以根据电磁学理论推导得到;当磁芯的长度大于螺线管的长度时,由于漏磁作用,(ΔZ/Z)_max与磁芯长度的关系偏离了线性关系,(ΔZ/Z)_max与磁芯长度的关系曲线中有一个极值点,(ΔZ/Z)_max在极值点达到最大.磁芯螺线管巨磁阻抗效应曲线的尖刺部分高度(ΔZ/Z)_T与磁芯长度的关系也有类似的极值点,(ΔZ/Z)_T在极值点达到最大值.磁芯螺线管巨磁阻抗效应曲线的尖刺部分对弱磁场敏感,受磁芯退磁场的影响明显,磁芯的退磁场与磁芯长度呈负指数关系. 关键词： 磁芯螺线管 FeCo基合金薄带 巨磁阻抗效应 磁芯长度     

On the envelope soliton near critical density in a plasma with cold ions and two-temperature electrons

Summary We have analysed the formation of envelope soliton near critical density in a plasma consisting of two-temperature electrons and cold ions. The non-linear Schr?dinger-like equation obtained isiφ _t +pφ _xx +q|φ|⁴φ=0 which we call the modified non-linear Schr?dinger equation. It is also observed that this approach leads to a physical situation where a linear combination of both the modified and usual NLS equations holds, in the formiφ _t +pφ _xx +q ₁|φ|²φ +q ₂|φ|⁴φ=0. It is demonstrated through graphical analysis thatq ₁,q ₂, thought of as a function of β(=T _el/T _eh), behave in opposite way. That is, whenq ₁ grows,q ₂ decays, or vice versa. Lastly we demonstrate that this equation can sustain a type of solution other than the usual solitary profile. The form of such a wave is also depicted graphically.     

Solitons in Josephson junctions: An overview

The dynamics of the Josephson tunnel junction is approximately described by a perturbed sine-Gordon equation. The Josephson tunnel junction is thus a convenient experimental solid state device for the study of solitons and solitonlike phenomena. The physical manifestation of the soliton is a propagating magnetic flux quantum ( ₀=h/2e=2.064×10^–15 V sec). Basic properties of the soliton and its relation to observable experimental quantities (zero field steps, microwave radiation, etc.) are reviewed. Recent direct measurements of the actual soliton profile are also mentioned.     

The mean velocity profile of near-wall turbulent flow: is there anything in between the logarithmic and power laws?

The question of possible analytical forms for the mean velocity profile in a near-wall turbulent flow is addressed. An approach based on the use of dispersion relations for the flow velocity is developed in the context of a two-dimensional channel flow. It is shown that for an incompressible flow conserving vorticity, there exists a decomposition of the velocity field into rotational and potential components, such that the restriction of the former to an arbitrary cross section of the channel is a functional of the vorticity and velocity distributions over that cross section, while the latter is divergence-free and bounded downstream thereof. By eliminating the unknown potential component with the help of a dispersion relation, a nonlinear integro-differential equation for the flow velocity is obtained. It is then analysed within an asymptotic expansion in the small ratio v_*/U of the friction velocity to the mean flow velocity. Upon statistical averaging in the lowest nontrivial order, this equation relates the mean velocity to the cross-correlation function of the velocity fluctuations. Analysis of the equation reveals existence of two continuous families of solutions, one having the power-law near-wall asymptotic U ～ yⁿ, where y is the distance to the wall, n > 0, and the other, U ～ ln?^p(y/y₀), with y₀ = const and p ≥ 1. In the limit of infinite channel height, the exponent n turns out to be asymptotically a universal function of the Reynolds number, n ～ 1/ln?Re, whereas p → 1. Thus, the logarithmic profile (p = 1) is found to be a member of the power-log family whose members with p > 1 are intermediate between the power- and logarithmic-law profiles with respect to their slopes at large y. These results are discussed in the light of the existing controversy regarding experimental verification of the law of the wall.     

Effect of aerosil dispersions on the nematic-to-isotropic interface

The effect of silica aerosils on the kinetics of the first-order nematic-isotropic (NI) phase transition is phenomenologically described in the framework of the time-dependent Landau-Ginzburg equation. A steady-state solution to the equation is presented such that the NI interface may propagate with a solitary-like wave profile under constant quenching. The results provide a plausible basis for the interpretation of the dynamical effects of quenched disorder in the liquid-crystal systems, caused by randomly interconnected porous media, such as aerosils. In the low silica aerosil ρ_s ( ≤0.1 g/cm^3) regime, the calculated values of the interface velocity v(T,ρ_s), the interface thickness κ(T,ρ_s), and the critical radius of a spherical nucleus of new nematic phase in a bulk isotropic environment, composed of polar molecules, such as 4-n-octyl- 4^′- cyanobiphenyl and 4-n-heptyl- 4^′- cyanobiphenyl shows that the effect of silica aerosils on the kinetics is reflected in a shifting of the set of temperature-dependent curves to lower temperature values.-1     

Scalar conservation laws with discontinuous flux function: I. The viscous profile condition

The equation , whereH is Heaviside's step function, appears for example in continuous sedimentation of solid particles in a liquid, in two-phase flow, in traffic-flow analysis and in ion etching. The discontinuity of the flux function atx=0 causes a discontinuity of a solution, which is not uniquely determined by the initial data. The equation can be written as a triangular 2×2 non-strictly hyperbolic system. This augmentation is non-unique and a natural definition is given by means of viscous profiles. By a viscous profile we mean a stationary solution ofu _t +(F ) _x =u _xx , whereF is a smooth approximation of the discontinuous flux, i.e.,H is smoothed. In terms of the 2×2 system, the discontinuity atx=0 is either a regular Lax, an under-or overcompressive, a marginal under- or overcompressive or a degenerate shock wave. In some cases, depending onf andg, there is a unique viscous profile (e.g. undercompressive and regular Lax waves) and in some cases there are infinitely many (e.g. overcompressive waves). The main purpose of the paper is to show the equivalence between a previously introduced uniqueness condition for the discontinuity of the solution atx=0 and the viscous profile condition.     

Ion volumes and an equation of state for plasma

A plasma equation of state in a gas domain is derived from Saha model accounting for ion cores. Calculations for Cu are performed using the stiff ion core model for densities of up to 10⁶ g/cm³. A compressible ion core model is also developed. The Tomas–Fermi model is applied to condensed plasma. Both models are unified into a thermodynamically consistent equation of state.     

Mean spherical approximation for a model liquid metal potential

The solution of the Ornstein-Zernike equation for a direct correlation function c(x) with damped oscillations and a hard core condition imposed upon the total correlation function h(x) has been proposed by Cummings as a means of treating a simple model potential for liquid metals in the mean spherical approximation [1]. Here some numerical results are given for this model and their significance is discussed. The solution of the Ornstein-Zernike equation is also extended; the hard core condition is generalized to a soft core condition, and Yukawa terms are added to the oscillatory c(x). Ways in which these extensions can be incorporated into more accurate liquid metal models, as well as into more accurate approximations for these models, are discussed. Finally, it is shown that our solution of the Ornstein-Zernike equation, after a change in the core condition, yields the structure of a spin glass model considered by Høye and Stell in the MSA-like approximation they propose [22].     

Renormalization of the Lorentz-Abraham-Dirac equation for radiation reaction force in classical electrodynamics

Dirac’s analysis of radiation reaction force in classical electrodynamics suggested that a 4-momentum not collinear with 4-velocity could be introduced for a radiating electron. This would be equivalent to renormalization of the electron mass as an operator relating these 4-vectors. Dirac also pointed to an arbitrary choice made in deriving the Lorentz-Abraham-Dirac (LAD) equation. It was shown that renormalization substantially modifies the LAD equation under the additional requirement that the standard relativistic relation ℰ² = p ² c ² + m ² c ⁴ holds for the renormalized energy and momentum. The renormalized LAD equation is more rigorous than the LAD equation, because the drawbacks of the latter are eliminated, and is simpler than a well-known approximation of the LAD equation. The renormalized LAD equation appears to be better suited for numerical simulations of processes in ultrahigh-intensity laser-pulse fields.     

Field theory onR×S 3 topology. I: The Klein-Gordon and Schrödinger equations

A Klein-Gordon-type equation onR×S ³ topology is derived, and its nonrelativistic Schrödinger equation is given. The equation is obtained with a Laplacian defined onS ³ topology instead of the ordinary Laplacian. A discussion of the solutions and the physical interpretation of the equation are subsequently given, and the most general solution to the equation is presented.