偏振光大气传输的前向散射新模型

建立了偏振光空间传输前向散射的物理模型。对各向同性散射介质,在非相干性假设条件下,导出了偏振光双散射和多散射前向散射的有效Mueller矩阵,给出了偏振光Mie散射前向有效Mueller矩阵各矩阵元之间的对称性关系,即Mueller矩阵的16个矩阵元中只有7个是独立的,其他9个矩阵元通过组合及一定角度的旋转即可得到。利用Monte Carol方法模拟了偏振光在空间传输10km的前向散射的有效Mueller矩阵,模拟结果表明各矩阵元存在一定的对称性关系,与基于本模型导出的偏振光前向散射的有效Mueller矩阵元具有较好的一致性。     

Single layer homogeneous model for surface roughness by polarized light scattering

In this paper a homogeneous single layer model for surface roughness by polarized light has been developed. It has been shown that the reflectance change in non-absorbing layer is directly proportional to the refractive index of the ambient and substrate media for s polarization but inversely proportional to the p polarization and it is directly proportional to the square of the thickness of the layer for both the polarization. In an absorbing layer, it has been shown that the thickness of the layer is equal to the twice of surface roughness of the single layer identical system for s polarization but it is ratio of twice of surface roughness to the square of refractive index of thin film for p polarization. The extinction coefficient of the layer is directly proportional to the thickness of that layer for both the polarization. The consequence of the scattered light on the specular reflectance and transmittance for oblique incidence shows that there is reduction in reflectance (in both non-absorbing and absorbing cases) and transmittance (in the absorbing case for p polarization only), due to roughness on the surface under the Drude effective-medium approximation. Thus such an absorbing layer provides a valid model for the effect of scatter on the transmittance for p polarization only.     

Multiple scattering of polarized light in a turbid medium

It is shown that multiple scattering of polarized light in a turbid medium can be represented as independent propagation of three basic modes: intensity and linearly and circularly polarized modes. Weak interaction between the basic modes can be described by perturbation theory and gives rise to “overtones” (additional polarization modes). Transport equations for the basic and additional modes are derived from a vector radiative transfer equation. Analytical solutions to these equations are found in the practically important cases of diffusive light propagation and small-angle multiple scattering. The results obtained are in good agreement with experimental and numerical results and provide an explanation for the experimentally observed difference in depolarization between linearly and circularly polarized waves.     

A systematic comparison between born approximation and distorted wave Born approximation for inelastic electron scattering

The correction factors for Coulomb effects in inelastic electron scattering are given for electric quadrupole transitions. The cross sections in Born approximation and distorted wave Born approximation are calculated in the liquid drop model for electron energies between 20 and 80 MeV and nuclei up toZ=26.     

Angle step selection for geometrical-optics approximation in light scattering

On the basis of the Shannon sampling theorem, we present a relationship between the maximal scattering angle step and the radius of particles in the calculation of light scattering intensity distribution. For the first rainbow intensity application, the relationship between the maximal scattering angle step and radius of particles is derived from that between the ripple frequency and radius and refractive index of particles using this method. For the geometrical-optics approximation, the incident angle is used to calculate the scattering intensity distribution. To get the highest speed, the maximal incident angle step is necessary. The relationship between the maximal step of incident angle and radius of particles is deduced from the maximal scattering angle step equation. As indicated by our result, the maximal step of the incident angle is not a constant and it varies with incident angle.     

Temperature dynamics of polarized and depolarized light scattering in a critical mixture

The results of Rayleigh line wing width, Landau-Placzek ratio and hypersound velocity temperature dependence at approaching the critical temperature of the exfoliating mixture of n-hexadecane-β, β'-dichlordiethyl ether are given.     

Local and non-local curvature approximation: a new asymptotic theory for wave scattering

Abstract

We present a new asymptotic theory for scalar and vector wave scattering from rough surfaces which federates an extended Kirchhoff approximation (EKA), such as the integral equation method (IEM), with the first and second order small slope approximations (SSA). The new development stems from the fact that any improvement of the ‘high frequency’ Kirchhoff or tangent plane approximation (KA) must come through surface curvature and higher order derivatives. Hence, this condition requires that the second order kernel be quadratic in its lowest order with respect to its Fourier variable or formally the gradient operator. A second important constraint which must be met is that both the Kirchhoff approximation (KA) and the first order small perturbation method (SPM-1 or Bragg) be dynamically reached, depending on the surface conditions. We derive herein this new kernel from a formal inclusion of the derivative operator in the difference between the polarization coefficients of KA and SPM-1. This new kernel is as simple as the expressions for both Kirchhoff and SPM-1 coefficients. This formal difference has the same curvature order as SSA-1 + SSA-2. It is acknowledged that even though the second order small perturbation method (SPM-2) is not enforced, as opposed to the SSA, our model should reproduce a reasonable approximation of the SPM-2 function at least up to the curvature or quadratic order. We provide three different versions of this new asymptotic theory under the local, non-local, and weighted curvature approximations. Each of these three models is demonstrated to be tilt invariant through first order in the tilting vector.     

Elastic scattering of electrons on nuclei with allowance for the second born approximation

In the framework of the shell model of light nuclei, the contribution to the scattering cross section of the second Born approximation due to the interference between the electric Coulomb interaction and the magnetic-dipole interaction is calculated. The case of backward scattering is considered. For not too high energies of the incident electrons, convenient approximate expressions are obtained for the correction to the cross section.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 12–15, January, 1981.     

Manifestation of the second-order alignment in light scattering by polarized atoms

An expression for the cross section of light scattering by axisymmetrically aligned atomic systems is derived in a compact form. The cross section under consideration is proportional to the state multipole of the fourth rank. The effect of the second-order alignment determined by the fourth-rank state multipole on the polarization and the angular distribution of scattered light is investigated. The polarization of incident light can be arbitrary and, in the general case, is specified by the Stokes parameters. In particular, it is demonstrated that the second-order alignment cannot induce circular polarization of scattered light and does not influence the dissipation-induced effects of circular dichroism associated with the first-order alignment but leads to a change in the angular distribution and the degree of linear polarization of the scattered light.     

Possible polarized neutron-nucleus scattering search for a new spin-dependent nucleon-nucleon coupling in the fermi range

An experimental opportunity is presented for the future to measure possible P- and T-non-invariant axion-like interaction between nucleons in the Fermi range. This interaction may be searched for in the measurement spin-dependent asymmetry of scattering of polarized neutrons in a keV-MeV energy range by heavy nuclei.     

Illustration of a bimodal system in Intralipid-20% by polarized light scattering: experiments and modeling

Intralipid suspensions behave like phantoms of human tissues concerning their light scattering properties. We present experimental measurements of the angular distribution of polarized light scattering at various incidence angles on Intralipid-20%. A comparison of the absolute values of these measurements with simulations using a vector radiative transfer model (N-flux) developed for multilayered media demonstrates a stratified structure of the samples with a double distribution of the size of scatterers. This result is confirmed by polarimetry imaging.     

Specific features of depolarized and polarized light scattering in a solution with a layering isolated region

Intensities of depolarized and polarized light scattering in guaiacol-glycerin solutions with layering isolated regions are measured. It is shown that (a) the depolarized scattering intensity is the same above the higher critical point (HCP) and below the lower critical point (LCP), and (b) the polarized scattering intensity below LCP is higher, the higher the HCP. An empirical formula is offered to describe the polarized scattered light intensity. No increase in the single depolarized scattering intensity is found approaching LCP and HCP.     

ScattPy: A new Python package for light scattering computations

We present a Python package developed for computing optical properties of non-spherical particles. It gives a user friendly flexible framework that takes advantage of programming with the modern language supported by the abundant library of scientific packages. The framework is designed to include the methods and interfaces to third-party codes required to treat scatterers of different shape and structure. We describe the current state of our package called ScattPy, briefly outline its range of applicability and note its outstanding accuracy for inhomogeneous particles with a multilayered structure.We also demonstrate some advantages of the ScattPy in particular when performing large-scale computations. Such languages as Python are known to simplify the data input and allow one to include new classes and objects (e.g. those required to define new scatterer shapes) without recompiling the code. The main benefits come from their ability to organize easily the output data as a database. In the ScattPy we use the SQLite database and illustrate how it is utilized in our investigation of the phase function dependence on the shape, size and structure of spheroids. By comparing the time consumption of the ScattPy to that of an equivalent code written completely in FORTRAN we show that there can be no essential performance losses when using Python.     

Deep inelastic scattering of neutrinos and antineutrinos by a polarized proton in the quark-parton model

Deep inelastic scattering of neutrinos and antineutrinos by polarized protons is considered in the quark-parton model. For processes with charged currents, a connection is obtained between the asymmetry of the differential cross sections corresponding to different spin directions of the target proton and the distribution functions of the polarized partons in the polarized proton (d for neutrinos and u for antineutrinos). It is shown that the presence of an x dependence of the asymmetry parameter corresponds to a difference between the distribution functions of partons with opposite helicity. For processes with neutral currents, relations are obtained between the asymmetry parameters and the constants that determine the helicity structure of the weak neutral quark current.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 4, pp. 41–45, April, 1980.I thank Professor B. K. Kerimov and A. É. Astratyan for a helpful discussion of the work.     

Buckling in a solid Langmuir monolayer: light scattering measurements and elastic model

Above a surface pressure threshold , we detect a buckled state in the low temperature solid phase of a phospholipid monolayer spread at the air-formamide interface. Stable ripples are observed with a Brewster angle microscope, and light scattering provides measurements mNm^-1, wavelength m and amplitude of a few nm for the deformation. A model, coupling the monolayer thickness and elongation, and consistent with the monolayer texture, is also presented. Received: 18 August 1997 / Revised: 9 December 1997 / Accepted: 29 January 1998     

Testing the Weinberg-Salam model in polarized ed and ep deep inelastic scattering

Three independent tests of the Weinberg-Salam model in polarized ed and ep deep inelastic scattering are discussed for which the theoretical predictions depend only weakly on parton-model assumptions.