Scattering characteristics of conducting cylinder coated with nonuniform magnetized ferrite

An analytical technique, referred to as the scattering matrix method （SMM）, is developed to analyse the scattering of a planar wave from a conductolution for the nonuniform fering cylinder coated with nonuniform magnetized ferrite. The SMM srite coating can be reduced to the expressions for the scattering and penetrated coefficients in four particular cases： nonuniform magnetized ferrite cylinder, uniform magnetized ferrite-coated conducting cylinder, uniform ferrite cylinder as well as homogeneous dielectric-coated conducting cylinder. The resonant condition for the nonuniform ferrite coating is obtained. The distinctive differences in scattering between the nonuniform ferrite coating and the nonuniform dielectric coating are demonstrated. The effects of applied magnetic fields and wave frequencies on the scattering characteristics for two types of the linear profiles are revealed.     

Pressure-induced structural transition of nonionic micelles

We report dynamic light scattering and small angle neutron scattering studies of the pressure-induced structural transition of nonionic micelles of surfactant polyoxyethylene 10 lauryl ether (C12E10) in the pressure range 0 to 2000 bar. Measurements have been performed on 1 wt% C12E10 in aqueous solution with and without the addition of KF. Micelles undergo sphere to lamellar structural transitions as the pressure is increased. On addition of KF, rod-like micelles exist at ambient pressure, which results in rod-like to lamellar structural transition at a much lower pressure in the presence of KF. Micellar structural transitions have been observed to be reversible.      

A Critical Examination to the Unitarized IJ ＝ 20 ππ Scattering Chiral Amplitude

We discuss the Padé approximation to the ππ scattering amplitudes in one-loop chiral perturbation theory.The approximation restores unitarity and can reproduce the correct resonance poles,but the approximation violates crossing symmetry and produces spurious poles on the complex s plane and therefore plagues its predictions in some cases.However we find that one virtual state in the IJ = 20 channel may have physical relevance.     

基于少模光纤的SBS光谱阈值特性分析

受激布里渊散射会影响少模光纤传输系统中的信噪比、传输距离与传输容量,是影响传输系统入纤功率提高的重要因素。对阶跃型少模光纤的受激布里渊散射谱的阈值进行了研究,运用了布里渊散射谱、模式联运谱的数学模型对少模光纤散射特性进行了分析,探讨了少模光纤布里渊散射增益谱、阈值增益系数,以及光纤各参量对少模光纤阈值的影响。分析结果表明：SI-10阶跃型少模光纤中存在五种不同的传播模式,不同模式有各自的传输常数以及有效折射率,各模式相互作用导致模式展宽、增益降低,且布里渊散射谱峰值增益系数为3.9×10-11 m·W-1。阈值增益系数受到光纤传感距离的影响,在相对较短距离传输中阈值急速下降,且其趋势随长度增加渐趋平缓,当光纤长度达到22 km时阈值增益系数趋于常数18.1。少模光纤的阈值因光纤长度的递增而递减,且递减趋势渐缓趋于常数20.5 dBm;少模光纤不同模式受激布里渊散射的阈值也因光纤长度的递增而递减最终趋于常数,且不同模式的阈值因模式阶数的递增而递增;少模光纤的阈值随着光纤衰减系数和纤芯半径的递增而递增,且增加趋势缓慢增大。不同衰减系数的光纤其阈值在不同长度趋于常数,衰减系数越大受激布里渊散射阈值越大越容易趋于一常数。     

Compton散射对固体中激光能量与光声信号强度关系的影响

应用光声理论、相对论量子理论和电子与多光子集团非线性Compton散射模型,研究了Compton散射对掺杂固体中光声信号强度的影响。结果表明,当掺杂固体中发生电子与多光子集团之间的多光子非线性Compton散射时,在忽略光声转换效率的变化和基质晶格对介电函数贡献的情况下,耦合激光能量和磁感应强度是影响光声信号强度的两个主要因素,其中耦合磁感应强度起主导作用。Compton散射使光声信号强度随耦合光的磁感应强度和能量的增大而迅速增大。能量与光声信号声压之间存在对数线性关系,但它相对于Compton散射前的曲线下移。     

Large supramolecular structures in water-alcohol mixtures evidenced by elastic light scattering

Summary We report the results of different light scattering experiments, both elastic and quasi-elastic, performed as a function of temperature at different concentrations on a water-butoxyethanol (C₄E₁) mixture. The comparison of the obtained data with the results of SANS gives evidence of the amphiphilic character of the alcohol molecules. In particular, we observe such a property gives rise to a well-defined micellarlike structure. At low temperatures (T≤5°C) we find that the mixture exhibits a surprising behaviour, namely very large structures (of the order of 2000 ?) built by an intermicellar aggregation process. In addition when the light scattering data show the presence of such large aggregates, neutron data reveal the persisting presence of micelles of about 20 ?. Such a structural picture agrees with the behaviour of the viscosity data. Due to the relevance of its scientific content, this paper has been given priority by the Journal Direction.     

Scattering and Bound States of the Dirac Particle for q-Parameter Hyperbolic Pöschl-Teller Potential

The one-dimensional Dirac particle for equal scalar and vector asymmetric q-parameter hyperbolic PöschlTeller potential (qHPT) is solved in terms of hypergeometric functions. The scattering and bound states are obtained by using the properties of the equation of continuity of the wave functions. We calculat in details the transmission and reflection coefficients.     

Photoelectron spectroscopy measurements of the valence band structures of polymerized thin films of C60 and La0.1C60

The electronic valence band structures of polymerized thin films of C₆₀ and La_0.1C₆₀ have been studied by using ultra-violet photoelectron spectroscopy. Additionally, the films have been characterized by using Raman spectroscopy, X-ray photoelectron spectroscopy, and X-ray diffraction. The valence band of the C₆₀ film shows major peaks at binding energies of 2.6, 7.2, 10.3, and 12.6 eV. In the case of the doped film, we observe (i) an additional peak with a binding energy of 13.7 eV, (ii) evidence for redistribution of the density of electronic states due to hybridization between the 5d orbitals of La and the C₆₀ cage, and (iii) significantly higher density of the electronic states near the Fermi energy. The valence band spectra of the doped film are in good agreement with recent results of the density functional theory that support strong hybridization between the d-valence orbitals of La and the C₆₀ cage.     

Prediction of structure-dependent charge transfer rates for a Li atom outside a Si(0 0 1) surface

We investigate the broadening of the 2s energy level of a Li atom outside a Si(0 0 1) surface using a first principles approach. The covalent nature of the Si surface produces large variations in Li energy level widths as a function of lateral position across the surface. The widths above symmetric Si dimers are predicted to be much larger than above buckled Si dimers, suggesting that charge transfer will occur primarily above symmetric dimers. We discuss the ramifications of our results on the controversy surrounding the relative abundance of the buckled vs. symmetric dimers on the Si surface.     

An improved variational method

In order to improve the unitarity of the S-matrix, an improved variational formulism is derived by proposing new generating functionals and adopting proper asymptotic boundary conditions for trial relative wave functions. The formulas with the weighted line-column balance for the single-channel and multi-channel scatterings, where the non-central interaction is implicitly considered, are presented. A numerical check is performed with a soluble model in a four coupled channel scattering problem. The result shows that the high accuracy and the unitarity of the S-matrix are reached.     

Atoms interacting with a metal surface with adsorbates: local and non-local effects on the charge transfer

A model system representing a collisional Li atom interacting in the “on top” geometry with an Al surface partly covered with Li adsorbates is studied. The cases of a unique adsorbate and of a uniform adsorbate layer are considered and compared. The energies and widths of the atom levels are much modified in the vicinity of the adsorbate. This is interpreted in terms of molecularisation of the atomic and adsorbate levels. These results also determine the relative importance of the local and non-local effects of the adsorbates on the resonant charge transfer process in atom-surface collisions.     

High sampling-rate measurement of turbulence velocity fluctuations in Mach 1.8 Laval jet using interferometric Rayleigh scattering

Interferometric Rayleigh scattering diagnostic technique for the time-resolved measurement of flow velocity is studied. Theoretically, this systematic velocity-measured accuracy can reach up to 1.23 m/s. Measurement accuracy is then evaluated by comparing with hot wire anemometry results. Moreover, the distributions of velocity and turbulence intensity in a supersonic free jet from a Laval nozzle with a Mach number of 1.8 are also obtained quantitatively. The sampling rate in this measurement is determined to be approximately 10 k Hz.     

Phase-modulated Autler–Townes splitting in a giant-atom system within waveguide QED

The nonlocal emitter-waveguide coupling, which gives birth to the so called giant atom, represents a new paradigm in the field of quantum optics and waveguide QED. We investigate the single-photon scattering in a one-dimensional waveguide on a two-level or three-level giant atom. Thanks to the natural interference induced by the back and forth photon transmitted/reflected between the atom-waveguide coupling points, the photon transmission can be dynamically controlled by the periodic phase modulation via adjusting the size of the giant atom. For the two-level giant-atom setup, we demonstrate the energy shift which is dependent on the atomic size. For the driven three-level giant-atom setup, it is of great interest that, the Autler–Townes splitting is dramatically modulated by the giant atom, in which the width of the transmission valleys (reflection range) is tunable in terms of the atomic size. Our investigation will be beneficial to the photon or phonon control in quantum network based on mesoscopical or even macroscopical quantum nodes involving the giant atom.     

Carbide precipitates in solution-quenched PH13-8 Mo stainless steel: A small-angle neutron scattering investigation

This paper deals with the small-angle neutron scattering (SANS) investigation on solution-quenched PH13-8 Mo stainless steel. From the nature of the variation of the functionality of the profiles for varying specimen thickness and also from the transmission electron microscopy (TEM), it has been established that the small-angle scattering signal predominantly originates from the block-like metallic carbide precipitates in the specimen. The contribution due to double Bragg reflection is not significant in the present case. The single scattering profile has been extracted from the experimental profiles corresponding to different values of specimen thickness. In order to avoid complexity and non-uniqueness of the multi-parameter minimization for randomly oriented polydisperse block-like precipitate model, the data have been analyzed assuming randomly oriented polydisperse cylindrical particle model with a locked aspect ratio.     

How does the S11 N*(890) state emerge from a naive K-matrix fit?

We give a pedagogical analysis on K-matrix models describing the πN scattering amplitude, in S₁₁ channel at low energies. We show how the correct use of analyticity in the s-channel and crossing symmetry in t- and u-channels leads to a much improved analytic behavior in the negative s region, in agreement with the prediction from chiral perturbation amplitudes in its validity region. The analysis leads again to the conclusion that a genuine N*(890) resonance exists.     

Spontaneous condensation in DNA-polystyrene- b-poly(l-lysine) polyelectrolyte block copolymer mixtures

We investigated the condensation of calf thymus DNA by amphiphilic polystyrene_m-b-poly(l-lysine)_n block copolymers ( PS_m-b- PLys_n, m, n = degree of polymerization), using small-angle X-ray scattering, polarized optical microscopy and laser scanning confocal microscopy. Microscopy studies showed that the DNA condenses in the form of fibrillar precipitates, with an irregular structure, due to electrostatic interactions between PLys and DNA. This is not modified by the presence of hydrophobic PS block. Scattering experiments show that the structure of the polyplexes corresponds to a local order of DNA rods which becomes more compact upon increasing n. It can be concluded that for DNA/ PS_m-b- PLys_n polyplexes, the balance between the PLys block length and the excess charge in the system plays an essential role in the formation of a liquid crystalline phase.     

Measurement of M-shell X-ray production cross sections for the element 73 \leqslant Z \leqslant 83 using 5.96 keV photons

Total M-shell X-ray production cross sections (M XRF) of the some elements in the atomic number range were measured at 5.96 keV incident photon energy using a Si(Li) detector. The results are compared with the experimental and theoretical values in the literature.     

薄膜超构表面声扩散体扩散性能研究*

针对传统的声扩散体结构复杂、加工不便的缺点,该文提出了一种薄膜型声学超材料扩散体,通过有限元软件建立了扩散体的有限元模型。分析了薄膜张力、质量块大小及背腔深度对声波相位调控的影响,并与传统施罗德扩散体的扩散性能进行比较,发现调控后的薄膜超构表面声扩散体对声能的吸收降低,并使入射声能更均匀地向全方向扩散。在相同的尺寸情况下,与传统施罗德扩散体相比,薄膜超构表面声扩散体在所需频段内扩散性能更优,结构更优,体积更小,质量更轻,加工更方便,更适用于工程应用。     

Quantitative interpretation of the low-loss electron signal

Low-loss electron spectra from clean elemental standards of C, Si, Cr, Fe, Cu, Ag, and Au are presented and theoretically interpreted with the aid of two basic theories. One of these assumes a simple elastic scattering and Bethe loss regime in which the low-loss signal arises from primary electrons that have undergone a single large-angle scattering event and whose energy loss is described by the continuous slowing down approximation. However, better qualitative agreement with experiment is obtained when multiple elastic scattering is considered via the transport approximation for electron deflection. The simple low-loss electron detector used to obtain the data is also described.