[en] Theoretical analysis of diffraction by a suspension of particles implies that the recording instrument is ideal and does not affect the results of measurements. The basis theoretical assumption is that the light pumping is performed by an unbounded plane wave. However, the beams used in experiments are bounded and, in addition, often spatially incoherent. Thus, the experimental conditions inevitably differ from the theroetical model. This study is devoted to evaluating the divergences that appear under these conditions and the methods for decreasing them. 16 refs., 3 figs

[en] A new method is suggested for theoretical analysis of the process of light scattering by the suspension of transparent spheres. The method is based on the spectral expansion in the Kotel'nikov-Shannon choice functions. The method suggested is simple and allows one to obtain a clear physical picture for all solution stages. Despite its approximate character, the method leads to solutions that fully coincide with the results from exact computations. In addition, this method allows one to take into account the fundamental instrumental effects. The second part of this paper is devoted to this problem. 11 refs., 5 figs

[en] The power of an optical signal detected upon nonstationary irradiation of a randomly irregular surface in the case when mutual shading of surface elements is an essential factor is investigated. An expression for an average (over an ensemble of irregular surfaces) power detected in location of a surface with a Gaussian distribution of heights and inclinations by a δ-pulse under conditions of strong shadings is derived. Shading is shown to produce a substantial distortion of the shape of the echo signal. 6 refs., 1 fig

[en] The intensity of zero-angle static Rayleigh light scattering by a polymer solution containing associated species, all in equilibrium with each other, can be calculated by introducing the thermodynamic condition for equilibrium either at the start or at the end of the calculation. Provided all species have the same value of the specific refractive index increment, it is shown for Flory-Huggins systems that the same formula is obtained by both routes. 9 refs

[en] A method based on classical physics, utilizing the first two even moments of the depolarized collision-induced light-scattering spectrum at various temperatures to derive an empirical model for the pair-polarizability anisotropy of interacting molecules, with only one adjustable parameter, is described and applied to the spectra of Hg. Good agreement with ab initio results in the literature is obtained and profiles calculated with these models are in excellent agreement with experiment. (author)

[en] The history of development of the theory of light scattering and dispersion in gases is outlined, from the works of Rayleigh, Planck, and Mandelstam to those of Lorentz and Einstein. It is shown that of central concern in these studies was actually the problem of thermal fluctuations in a medium. A formula for the permittivity ε(ω) taking account of radiation friction forces is derived for the case of an isotropic medium. (methodological notes)

[en] One of the standard methods used to measure the hydrodynamic diameter of nanoparticles is photon correlation spectroscopy, especially dynamic light scattering (DLS). In principle, this technique is to analyze correlation function of the scattered light from the nanoparticles undergoing Brownian motion in solution and to calculate the diffusion coefficient from the correlation function which is converted into the hydrodynamic diameter. However, when using this technique, one needs to pay careful attention to interaction effects (i.e., particle-particle and particle-solvent interactions) on the diffusion coefficient of the particles in solution. If not, then incorrect information can be obtained on the self-diffusion coefficients of nanoparticles. In order to facilitate a strict procedure for obtaining real size of the nanoparticles in solution, we used 20 nm, 50 nm and 100 nm-nominal polystyrene latex (PSL) nanoparticle solutions for DLS measurement. We represented that a rigorous scrutinizing the concentration dependence of the diffusion coefficient of the PSL nanoparticles made it possible to separate the interaction effect from the diffusion phenomena of the PSL nanoparticles suspended in water and to give real size of the PSL nanoparticles.

[en] We present DDA investigations of light scattering by irregular particles whose size is comparable with wavelength. We consider four types of randomly irregular particles: strongly damaged spheres, rough-surface spheres, pocked spheres, and agglomerated debris particles. Each type of particle is generated with a well defined algorithm producing an ensemble of stochastically different particles that have a common origin. The different types of irregular particles produce different angular dependencies of intensity and linear polarization degree. Transformation of phase curves of intensity and polarization with changing size parameter for irregular particles tends to be more monotonic, unlike spheres. We find that the magnitude of the negative polarization branch (NPB) tends to shrink as particle absorption increases; whereas, the maximal value and position of the positive polarization branch tends to increase. The most frequently observed shape of the negative polarization at small phase angles is asymmetric with a shift of the minimum position towards the angle of polarization sign inversion. All types of considered irregular particles reveal such asymmetry at x<10. Symmetric negative polarization branches occur seldom. The necessary conditions for their appearance are a relatively large size parameter x≥10 to 12 and low absorption

No abstract available

No abstract available