Valery Filippov - Academia.edu (original) (raw)

Papers by Valery Filippov

Journal of Applied Spectroscopy, 2018

An algorithm is developed for solving the inverse problem of multiangular spectrophotometry of a ... more An algorithm is developed for solving the inverse problem of multiangular spectrophotometry of a layer on a planeparallel substrate of fi nite thickness using sand p-polarized waves. It allows the dispersive properties of the layer and substrate to be studied both far from and in the vicinity of the resonant wavelengths. The dispersive properties of layers of pure and Al-doped ZnO on glass substrates are investigated using it. It is shown that doping shifts the absorption band maximum to shorter wavelength and decreases the refractive index of the material. The applicability limits of known approximate expressions for determining the spectral dependence of the absorption coeffi cient of a layer from spectrophotometric data are estimated.

A technique to evaluate the accuracy with which the optical parameters of thin films are determin... more A technique to evaluate the accuracy with which the optical parameters of thin films are determined by the method of reflectance-spectrum extrema envelopes is presented. The general case of s-polarized light impinging obliquely on a weakly absorbing thin film formed on an absorbing substrate is discussed. Rather simple analytical expressions are derived which can easily be used in program realization on computers for calculating errors. On the basis of the error analysis, a procedure for determining the optical constants and thickness of thin films is proposed, which allows one to reach the maximum accuracy in solving the inverse problem of spectrophotometry. The optical constants and the thicknesses of the films of perylenetetracarboxylic acid and 2-[4-(4-aminophenyl)phenyliminomethyl]phenol formed on silicon substrates are found by the developed technique in the spectral range 550–900 nm.

Journal of Applied Spectroscopy, 2009

It is shown by numerical simulation that the enhancement of the field near metallic nanoparticles... more It is shown by numerical simulation that the enhancement of the field near metallic nanoparticles is most significant in the transparency region of the matrix material and falls off as the absorption coefficient rises. In an absorbing matrix medium this leads both to an increase in the fraction of energy absorbed by the matrix material and to a substantial transformation in its spectral distribution. This is illustrated for the case of copper phthalocyanine with silver nanoparticles. By choosing the size of the introduced plasmon nanoparticles it is possible to enhance the absorption in the visible for the materials used in solar cells and thereby increase their energy efficiency.

By the IR spectrophotometric method, metastable vacuum-deposited films of copper phthalocyanine a... more By the IR spectrophotometric method, metastable vacuum-deposited films of copper phthalocyanine and composites based on it have been investigated. For copper phthalocyanine films, an intense absorption band in the region of 729 cm−1, which appears at oblique incidence of linearly polarized radiation with oscillations lying in the incidence plane, has been established. Its origin is associated with the features of the supermolecular architecture of polycrystalline films particular, with the character of “packing” of copper phthalocyanine microcrystallites.

Optics and Spectroscopy, 2011

For spherical Cu, Ag, and Au nanoparticles with a radius of 1–3 nm in copper phthalocyanine (CuPc... more For spherical Cu, Ag, and Au nanoparticles with a radius of 1–3 nm in copper phthalocyanine (CuPc), with allowance for internal size effects, we calculate the scattering efficiency factor in the near zone, the extinction efficiency factor due to scattering and absorption of incident radiation, and the efficiency of the increase in absorption by the matrix material. This occurs in the CuPc absorption bands, as well as in the weak absorption region of CuPc, where, owing to surface plasmon resonance, an additional absorption band arises for nanoparticles of all three materials. For Ag nanoparticles, the increase in absorption is twice as high as for Cu and Au nanoparticles; for these it differs inconsiderably.

Crystallography Reports, 2007

The optical properties of a biaxial absorbing KGd(WO4)2:Nd3+ crystal have been investigated. The ... more The optical properties of a biaxial absorbing KGd(WO4)2:Nd3+ crystal have been investigated. The main refractive indices were measured in the visible spectral range and the absorption and transmission spectra of samples of these crystals were studied. The changes in the refractive indices were in the region of the absorption bands with the use of the Kramers-Kronig relation. Conoscopic pictures of this crystal in the regions of transparency and absorption bands were calculated and are presented.

$Research paper thumbnail of Spatial, polarization and angular characteristics of external conical refraction$

Optics Communications, 2017

Appearance of two rings of external conical refraction (ECR) is investigated theoretically within... more Appearance of two rings of external conical refraction (ECR) is investigated theoretically within the plane-wave approximation. The hollow cone of ECR is the cone of normals inside a crystal. Due to a birefringence, two sets of isonormal waves are related to the cone. One set forms a filament of rays directed along the biradial, and the other set generates the hollow cone of rays. The apex angle of the cone is nearly twice as large as that of the cone of normals and its axis is close to the direction of the biradial. After leaving the exit facet of a crystal plate, the ray filament spreads into a cone again, and the ray cone gives rise to a second outer cone so that two nonconcentric rings appear at a screen behind the plate. Polarization states at the neighbouring points of the rings lying on one radius are mutually perpendicular. Numerical calculations were performed for crystals with moderate and large optical anisotropy, namely KGd(WO 4) 2 , ammonium oxalate, L-N-(5-Nitro-2-peridyl) leucinol and sulfur. Dispersion of the angle of ECR, the apex angle of the cone of incident (from air) waves and the ray cone is calculated for three tungstate crystals, KGd(WO 4) 2 , KLu(WO 4) 2 , and KY(WO 4) 2 .

Journal of Applied Spectroscopy, 2007

Taking into account the contributions of interference and incoherent multiple reflections of ligh... more Taking into account the contributions of interference and incoherent multiple reflections of light in the substrate, we have determined the distribution of the absorbed energy density Q in layers of a multilayer photovoltaic cell in the general case of oblique incidence of light on the cell. The relations obtained are expressed in terms of the Fresnel reflection and transmission coefficients for interfaces between media, which for oblique incidence are different for s and p polarization of the incident light. The energy absorbed by an active layer of the cell varies very slightly with the angle of incidence if the maximum in the Q distribution is located at a heterojunction. We carried out a numerical analysis for a five-layer cell based on a copper phthalocyanine-fullerene heterojunction.

International Symposium on and National Conference on Acoustoelectronics. Program and Abstracts Surface Waves in Solid and Layered Structures

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