X-ray diffraction in a crystal with a linear lattice parameter variation

The dynamical X-ray diffraction in a crystal with a linear lattice parameter variation (LLPV) and its applications to the X-ray diffractional investigations of thin solid state films are studied. For the interpretation of the reflection coefficients angular dependence is the Fresnel layers construction developed. Some particular cases of the general diffractional problem solutions for the crystals with LLPV are treated.     

Direction of propagation of diffracted beams with variation in the orientation of a diffraction grating

This article considers the change in direction of diffracted beams as a result of changing the orientation of a diffraction grating. The conditions for beam invariance are considered. It is shown that invariant beams can be found even for the case of two-dimensional diffraction.Leningrad Institute of Precision Mechanics and Optics, Leningrad. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 6, pp. 27–30, June, 1994.     

Multislot microwave transmission lines fabricated on an insulating substrate covered with a ferroelectric film

A rigorous electrodynamic model is used to calculate the dispersion characteristics of multislot microwave transmission lines fabricated on a layered structure containing a ferroelectric film. The attenuation due to the finite conductivity of the metal electrodes is found.     

Kossel lines in extremely asymmetric diffraction schemes

It is demonstrated theoretically that the intensity distribution within the Kossel lines in an extremely asymmetric X-ray diffraction scheme has an anomalous shape of a sharp peak exceeding the background intensity by several hundred times. The possibility of experimental observation of this phenomenon is discussed.     

Method of moments in analysis of x-ray diffraction lines

A general relation between the moments of the functionsf,g, andh, in the integral equationh(x)=f(y)g(x–y) dy, is derived. This enables any moment of the unknown functionf to be calculated from the moments of the functionsg andh. In particular, if certain assumptions are fulfilled, the moments of the components of the doublet can be calculated with advantage from the moments of the total profile. The statistical significance of the moment characteristics is also emphasized.

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f, g, h h(x)=f(y)g(x–) dy, f g h. , . .

     

Echelle diffraction grating demultiplexers with a single diffraction passband

Planar multiplexers based on echelle gratings are very popular devices for optical communication applications. However, the available channel number is restricted by the concept of free spectral range (FSR) due to their high operating diffraction order. Now, we can break the restriction of the FSR concept, and most of wavelengths in the operating passband of echelle grating multiplexers can be used based on a variable diffraction order design. We present the design, fabrication, and characterization of the echelle grating multiplexer with a single diffraction passband based on silica platform.     

Transient analysis of microstrip lines with ferrite substrate by extended FD-TD method

In this paper, the wide band transient signal propagation characteristics along microstrip lines with ferrite substrate are presented. In the analysis how the frequency dependent media such as ferrite may be genearally fomulated by FD-TD method is described. the distortions of transient signal in Gaussian shape propagating along uniform or step junction microstrip are simulated by the extended FD-TD method. Results show the distinctive influence of applied DC magnetic field and magnetizaton on the dispersion of transient signal.     

Chromatic focusing of X-ray diffraction lines and achromatic camera

The conditions for simultaneous suppression of the wave-length component (broadening) and instrumental component (broadening) of the X-ray diffraction lines are analyzed. The fulfilment of the chromatic focusing conditions theoretically restrains the wave-length component as if we used an infinitely narrow wave-length interval in the incident beam. This is advantageous particularly in measuring the line profiles, as the precision of profile analysis can thus be appreciably increased. This paper presents general considerations and computations for a given experimental set-up. A camera suitable for this kind of measurement is described and the profile of a line with=74·3° in an achromatic arrangement and in an ordinary back-reflection camera is compared.     

Graphical solution of chromatic and geometric focusing of X-ray diffraction lines

A nomograph and a transparent chart, serving for the rapid determination of the simultaneous chromatic and geometric focusing of X-ray diffraction lines, are described.     

Double semiconductor substrate in overlay shielded superconducting microstrip lines

The Transverse Transmission Line (TTL) is used in the theory of the overlay shielded microstrip lines considering the superconductor strip on two semiconductor regions. The superconductor effect is included with the boundary condition of the surface impedance, that is related to the complex conductivity of the material, calculated from the advanced two-fluid model. Applying the moment method the complex propagation constant of the structure, including the phase constant and the attenuation constant, is obtained. Results are presented for the complex propagation constant, versus the frequency and the temperature, of this overlay superconducting microstrip lines.     

Modelling diffraction during ray tracing using the concept of energy flow lines

The ray-tracing with diffraction on facets (RTDF) model is suitable for rapid computation of scattering on faceted dielectric objects such as ice crystals. It combines ray tracing with diffraction on flat facets. The model calculates diffraction using an approximation for the far-field direction of the Poynting vector. In this paper, an estimate based on an approximation by Prosser for the electric and magnetic fields describing diffraction at a slit is used to calculate energy flow lines and their far-field deflection angles. Best-fit formulas describing the dependence of the far-field deflection angle on the size parameter, angle of incidence and the position of the flow line in the plane of the slit are derived and incorporated into the RTDF model. Phase functions for hexagonal columns are presented and compared with an analytic technique, the separation of variables method, and geometric optics with projected area diffraction.     

Structural investigation of thin tetracene films on flexible substrate by synchrotron X-ray diffraction

Structural properties of tetracene thin films grown by vacuum sublimation on a flexible Mylar^© substrate have been investigated by means of synchrotron X-ray diffraction. The films are polycrystalline and are made up of crystalline domains oriented with the (0 0 l) planes almost parallel to the substrate and completely misoriented around the surface normal. Two crystallographic phases (α and β thin film phases) have been identified. They differ for the d_h k l interplanar spacing, both larger than that of the bulk. As a comparison, results from tetracene films grown on SiO₂ have been reported to investigate the different charge transport properties of films grown on Mylar and on SiO₂ substrates.     

Sound diffraction by a barrier with a fan-shaped headpiece

With respect to a noise barrier, sound diffraction by a half-plane with a fan-shaped headpiece is calculated. The fan consists of a set of rigid strips of different widths, which form narrow wedge-shaped channels of different lengths. The channels are connected to each other through the inner cylindrical cavity into which the inner open ends of the channels face. The curves representing the degree of sound suppression as a function of the frequency and the angle of incidence of sound waves are calculated. These curves demonstrate the high efficiency of the proposed barrier.     

菲涅耳深区散斑强度统计特性及演化

利用直透光波和高斯散斑场的叠加理论和基尔霍夫近似研究了菲涅耳深区散斑的构成,给出了菲涅耳深区散斑场及其强度概率密度和对比度的表达式.利用原子力显微镜测量的随机散射表面高度分布数据模拟菲涅耳深区不同散射距离处散斑,并计算绘出其强度概率密度和对比度曲线.理论与模拟相结合研究这两个统计函数的特征和直透光强所占比例的影响,以及它们随散射距离的演化规律.     

分离X射线衍射线多重宽化效应的新方法和计算程序

在近似函数的基础上，提出并建立分离微晶与微应力、微晶与堆垛层错、微应力与堆垛层错二重宽化效应的最小二乘法和微晶-微应力-堆垛层错三重宽化效应的最小二乘法，同时编制了相关的计算机求解系列程序.这些方法适用于密堆六方(cph)、面心立方(fcc)和体心立方(bcc)结构.还给出和讨论了几个应用实例. 关键词： 最小二乘法 微结构 X射线衍射 计算程序     

Fuul-wave analysis for coupling characteristics of multiconductor microstrip lines on semiconductor substrate

Conclusion The coupling effects for multiconductor microstrip on semiconductor substrate are analyzed by full-wave spectral domain approach. It is believed that the contribution aforementioned will facilitate successful design of MMIC modules in millimeter wave band and very high-speed digital integrated circuits.     

Anchoring properties of substrate with a grating surface

The anchoring properties of substrate with a grating surface are investigated analytically. The alignment of nematic liquid crystal (NLC) in a grating surface originates from two mechanisms, thus the anchoring energy consists of two parts. One originates from the interaction potential between NLC molecules and the molecules on the substrate surface, and the other stems from the increased elastic strain energy. Based on the two mechanisms, the expression of anchoring energy per unit area of a projected plane of this grating surface is deduced and called the equivalent anchoring energy formula. Both the strength and the easy direction of equivalent anchoring energy are a function of the geometrical parameters (amplitude and pitch) of a grating surface. By using this formula, the grating surface can be replaced by its projected plane and its anchoring properties can be described by the equivalent anchoring energy formula.