Ab initio calculations of chloride complexes of Au, Hg, Tl, Pb, and Bi in anomalous oxidation states (2S1/2 electron state)

Ab initio calculations of chloride complexes of Au, Hg, Tl, Pb, and Bi in anomalous oxidation states (²S_1/2 electron state) were carried out by the Becke-Lee-Yang-Parr density functional method using the Dunning-Hay LanL2DZ basis set. Optimum geometric parameters and electronic characteristics of MCl _n (H₂O) _m ⁿ (n=1–4 andm=0,4,5) complexes were determined. In each of the considered series the spin, population on the central metal atom decreases as its atomic number increases. The energy of transition of the unpaired electron to the lowest unoccupied MO decreases in the same order. The unpaired electron occupies an orbital that is mostly a linear combination of the s-orbital of the metal atom and the p-orbital of the Cl atom (the antibonding σ-orbital of the M−Cl bond). Distinctions in the changes in spectral properties of aquacomplexes and chloride complexes in isoelectronic series, observed as the degree of oxidation of the metal atom increases, were explained. The results of calculations are in agreement with the experimental data obtained by ESR and optical spectroscopy. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1049–1055, June, 1999.     

法拉第反常色散滤光器透射谱的普遍计算方法

报道了一种计算法拉第反常色散滤光器（ＦＡＤＯＦ）透射谱的普遍方法,该方法可计算不同碱金属元素工作在任意电偶极跃迁和任意磁场强度下的法拉第反常色散滤光器透射谱,对主动式和被动式法拉第反常色散滤光器同样适用,该方法还可进一步推广到其它类型的原子滤光器（如斯塔克型原子滤光器）的计算,给出了采用这种方法对铷主动式７７５．９ｎｍ法拉第反常色散滤光器透射谱的计算结果,与实验曲线符合较好。     

The Temperature Zero Limit

We prove that, for a broad class of many-fermion models, the amplitudes of renormalized Feynman diagrams converge to their temperature zero values in the limit as the temperature tends to zero.     

三能级级联型介质的正常色散与反常色散

建议利用三能级级联型介质实现从正常色散到反常色散的变换.在级联型介质中,两个偶极跃迁分别与两个不同的相干场耦合.探测场或者与上跃迁耦合,或者与下跃迁耦合.利用谐振展开方法把介质密度矩阵元方程组转换成在定态条件下系数不依赖时间的方程组,然后用逆矩阵求解,并用此解求得介质的吸收与色散谱.结果表明,对于每一种情形,在同一频率区域系统既能呈现正常色散,也能呈现反常色散.通过改变耦合到探测跃迁的驱动场强度,可以实现从正常色散到反常色散的转换.级联系统与Λ和V系统之间呈现两个差别.第一,如果利用Λ和V系统的两个跃迁同时与探测场耦合获得色散转换,则需要利用近简并能级,而本方案利用缀饰态获得等价的近简并能级,其间距由相应驱动场强度进行控制.第二,如果利用Λ和V系统的单个跃迁耦合探测场建立色散转换,当退耦合态起主要作用时,系统不能产生色散转换,而级联系统不涉及退耦合态.     

Modeling of penetrant diffusion in glassy polymers with an integral sorption deborah number

A mathematical model was developed to explain the anomalous penetrant diffusion behavior in glassy polymers. The model equations were derived by using the linear irreversible thermodynamics theory and the kinematic relations in continuum mechanics, showing the coupling between the polymer mechanical behavior and penetrant transport. The Maxwell model was used as the stress–strain constitutive equation, from which the polymer relaxation time was defined. An integral sorption Deborah number was proposed as the ratio of the characteristic relaxation time in the glassy region to the characteristic diffusion time in the swollen region. With this definition, an integral sorption process was characterized by a single Deborah number and the controlling mechanism was identified in terms of the value of the Deborah number. The model equations were two coupled nonlinear differential equations. A finite difference method was developed for solving the model equations. Numerical simulation of integral sorption of penetrants in glassy polymers was performed. The simulation results show that (1) the present model can predict Case II transport behavior as well as the transition from Case II to Fickian diffusion and (2) the integral sorption Deborah number is a major parameter affecting the transition. © 1993 John Wiley & Sons, Inc.     

Lepton distribution in top decay: A probe of new physics and top-polarization

We investigate the possibilities of studying new physics in various processes of t-quark production using kinematical distributions of the secondary lepton coming from decay of t quarks. We show that the angular distributions of the secondary lepton are insensitive to the anomalous tbW vertex and hence are pure probes of new physics in a generic process of t-quark production. The effects of t polarization on the distributions of the decay lepton are demonstrated for top-pair production process at a γγ-collider mediated by a heavy Higgs boson.      

Coupling effect of surface plasmon polaritons in single-negative lamellar heterostructure

Propagation characteristics of surface plasmon polaritons (SPPs) in the lamellar heterostructure, which is actually a SPP waveguide array, constructed by two kinds of single negative (SNG) material layers stacked alternatively are investigated. Based on the finite element method (FEM), the negative-refraction (NR) property is demonstrated when the electromagnetic wave penetrates through free space into such SNG lamellar structure. A clear view of the underlying physics of NR is presented qualitatively that is mainly related to the coupled SPPs. The strong coupling effect leads to the novel SPP dispersion curves and then the anomalous propagation characteristics.     

Spectrum of Light Reflection From a Quasiperiodic Structure of a Dielectric

In the present work, we show that for quasiperiodic gratings that are described by definite functions it is possible to substantially decrease the amplitude of side peaks in the spectral dependence of the reflection factor. The results of numerical integration of a system of differential equations that describe the propagation of waves in a quasiperiodic medium indicate that with an increase in the number of first derivatives of the functions that have zero values on the grating edges the attenuation of the side peaks increases. Analysis of the spectral dependence of the reflection factor for certain functions is carried out.     

Modelling of linearly chirped fiber Bragg gratings by the method of single expression

To model chirped fiber Bragg gratings (FBGs) for dispersion compensation in optical fibers a novel method of single expression (MSE) is used. The reformulation of Helmholtz's equation in the MSE to the full set of first-order differential equations leads to dealing with the electric field amplitude, its derivative, power flow density and phase distributions in any aperiodic media. The phase derivative obtained numerically permits to compute the dispersion slope in the time delay of investigated chirped gratings. Reflective and time delay spectra of linearly chirped gratings of different lengths and chirp coefficients are computed. A self-similarity law for the gratings of the same strength but different lengths and chirp coefficients is revealed. The apodization of gratings is applied to reduce sidelobes in gratings' reflection spectra and eliminate oscillations in the time delay characteristics.     

Measurements of near millimeter wave atmospheric attenuation in the temperature range 259K to 282K

Field measurements of absorption of near millimetre waves by the atmosphere at temperatures below 280°K have confirmed that there is an additional absorption component characterised by a much larger temperature exponent than can be attributed to water dimers in equilibrium.