Leonid Poperenko

Leonid Poperenko
Taras Shevchenko National University of Kyiv | Київський національний університет імені Тараса Шевченка · Faculty of Physics

Professor

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178
Publications
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Publications

Publications (178)
Data
Talbot image formation on the stepped surface
Presentation
Full-text available
The phenomenon of Talbot image formation on the stepped surface is described and demonstrated both theoretically and experimentally. The Talbot self-image shift on the surface step is observed and implemented for the measurement of the three-dimensional step height of a large discontinuous object with optically plane surface. Due to the fact that t...
Article
The multiple-angle-of-incidence ellipsometric studies of the natural film formed on the surface of porous silicon sample after its production and subsequent keeping in isopropyl alcohol have been performed. A new property of porous silicon with the natural film on its surface has been revealed which consists in a drastic change of the polarization...
Article
Full-text available
Degenerate four-wave mixing (DFWM) processes in carbon disulfide have been experimentally studied applying the wavelength dependent femtosecond laser source. The quantum mechanical perturbation theory was applied to analyze the experimental data. Third-order optical nonlinearity in carbon disulfide has been proposed to consider two- or three-energy...
Article
Optical properties of a transient layer with a broken structure that arises at the surface of optical glass at its treatment have been considered. Rather often, the surface of optical elements is considered to be perfect, although the actual inhomogeneous surface structure can have a significant effect for precision physical experiments or novel te...
Chapter
Optical properties of zirconium-based amorphous alloys that were subjected to deuterium plasma treatment have been investigated by the multiple-angle-of-incidence single-wavelength and spectral ellipsometry in a spectral range of 0.5–3.5 eV. After bombardment by ions of deuterium plasma of the samples the increase in the intensity of absorption wit...
Chapter
Optical properties of non-treated silicon plates and Si plates modified by femtosecond laser irradiation have been investigated by ellipsometry. The samples of the nanostructured silicon as isolated cells were formed on the single-crystal silicon wafers by a method of the laser ablation. Laser beam scanning modes provide the synthesis of nanostruct...
Conference Paper
The results of ellipsometric diagnostic of femtosecond laser welded fused silica-silica, fused silica-copper and fused silica-silicon samples are presented. The bonded interface of each sample is composed of numerous laser weld seams at their periphery in a closed shape pattern so as to seal the inner part due to optical contact of two species. The...
Article
Full-text available
Channels of the ¹³⁷Cs and potassium transfer from soil to plants in the field under waterstressed conditions are investigated. Different rapidly maturing plants were grown and selected simultaneously several times during the 2012 and 2013 seasons at the same experimental sites with different soil types under natural conditions at the Chornobyl 10-k...
Article
Full-text available
Electrostriction forces during laser ablation have been studied both theoretically and experimentally. The components of electroctrostriction force for inhomogeneous electromagnetic field near a substrate were proposed to be taken similarly to those in gases within nonresonant spectral region. Nonzero Lorentz force in standing light wave was found...
Conference Paper
The spectroellipsometer based on DMR-4 spectrometer was automated. An electronic system and software for the automation of equipment was designed and built. The system was calibrated and for the purpose of verification of optical constants of metals samples such as gold, silver and copper were measured. The device automatically measures metal surfa...
Article
The optical properties of ultrathin Au and Sn islet films, obtained by the methods of magnetron sputtering and thermal evaporation, respectively, are considered in this paper. By measuring the Stokes vector of the beam reflected from the samples, polarized and depolarized radiation components were separated. The conditions of the polarization degre...
Article
In this paper, the angular ellipsometric studies of natural oxidized surface layer on silicon and gallium arsenide are carried out. The mean wavelength of probe radiation beam was λ = 625 nm, with FWHM = 10 nm. Angular dependencies of ellipsometric parameters ψ and Δ (azimuth of restored linear polarization and phase shift between p- and s- compone...
Article
Full-text available
Concentrations of 137Cs and potassium in solutions extracted by centrifugation from soils selected at some experimental sites in the 10-km Exclusion Zone of Chornobyl Nuclear Plant were determined. The results showed that for the majority of investigated soils, the concentration of 137Cs in soil solution depends on the humidity of the soil before c...
Article
Full-text available
Surface of highly oriented pyrolytic graphite with terrace steps was studied using scanning tunneling microscopy with high spatial resolution. Spots with positive and negative charges were found in the vicinity of the steps. Values of the charges depended both on the microscope needle scan velocity and on its motion direction. The observed effect w...
Article
The optical properties and surface structure of graphene films grown on thin copper Cu (1 μm) layer using chemical vapour deposition method were investigated via spectroscopic ellipsometry and nanoscopic measurements. Angle variable ellipsometry measurements were performed to analyze the features of dispersion of the complex refractive index and op...
Article
Interaction of highly viscous polystyrene suspensions of light-absorbing microparticles with pulsed radiation of a Q-switched YAG:Nd3+ laser is investigated. Absorption of laser radiation by the suspended microparticles causes thermal decomposition (pyrolysis) of the polymer in the vicinity of the overheated particles. Laser-induced incandescence (...
Book
Full-text available
Precision devices and instruments of optoelectronics : monograph Authors: L.V.Poperenko, V.S.Staschuk, I.A.Shaikevitch, V.S.Voittsenya, Yu.V. Kudryavtsev, V.A.Sterligov, A.V.Stronski, G.S.Tymchik, V.G.Kolobrodov, S.I.Chernyak. Ukraine, Kyiv, “Kyiv University”, 2016.-712pp. ISBN 978-066-439-872-2 Results of development of physical bases which Наведе...
Article
Full-text available
Metal nanocrystals are actual objects for the modern biophysics mainly because of their usage in sensors based on localized surface plasmon resonance (LSPR) and as active substrates for surface-enhanced spectroscopies. This work deals with the experimental and theoretical investigation of optical properties of trigonal and hexagonal Au nanoprisms d...
Article
Full-text available
The effects of magnesium on the morphology of a fi lm of zinc oxide, its crystal structure, and its optical characteristics were studied. It was shown that with magnesium concentrations of up to 12% the zinc ions are substituted by magnesium ions without rebuilding the crystal lattice. The optical conductivity of the samples in the range of 1–4 eV...
Conference Paper
Full-text available
This research deals with consideration of the SPR sensor response in the framework of the scattering matrix approach with the modeling of biomolecular layer using Green's function formalism and effective medium theories. It was found out that modeling of the SPR sensor response using abovementioned approaches in the densely packed monolayer approxi...
Article
A method is proposed for determining the absorption coefficients of optical dielectric media. It is based on angular measurements of light fluxes. The absorption coefficients of laser radiation are determined for a number of optical samples at a wavelength of 655 nm. The proposed method of determining the absorption coefficients of optical dielectr...
Article
Two types of single beam laser traps have been built. Laser trap using visible light is used to optically trap micro-and nanosized polymer spheres. Laser trap using near infrared radiation is used to avoid optical damage when used to manipulate living cells. Manipulation of internal organelle was successfully demonstrated.
Article
The surface functional layers of commercial detector-grade CdTe crystals are characterized after different surface treatments such as chemical polishing etching in bromine-containing solutions and laser annealing with nanosecond pulses of the second harmonic of a YAG:Nd laser. The effects of etching and laser irradiation with energy density near th...
Article
On an example of poly(vinylidene fluoride - trifluorethylene) ferroelectric polymer we have shown how different optical methods can be applied for basic optical constants such as refractive index and absorption coefficient obtaining, scattering surface quality control, spectral transmission range control, examining polarization degree etc. Wide...
Article
Full-text available
Indium tin oxide (ITO) is a solid solution of indium (III) oxide (In 2 O 3 ) and tin (IV) oxide (SnO 2 ).It is a topical subject of research in modern physics. This material combines high transparency (in the visible area) and conductivity. It is used in the production of transparent electrodes of liquid crystal screens and solar cells. ITO paramet...
Conference Paper
Full-text available
Indium tin oxide (ITO) is a solid solution of indium (III) oxide (In2O3) and tin (IV) oxide (SnO2). It is a typical object for research in modern optoelectronics. This material combines high transparency (in the visible) and conductivity simultaneously. It is used in the production of transparent electrodes of liquid crystal screens and solar cells...
Article
Full-text available
We present our investigations on the enhancement of magneto-optical (MO) effects in multilayer NiFe/Ag(Au,Cu) thin films. A strong enhancement of the polar MO activity is observed when surface plasmon polaritons (SPPs) are excited in the Kretschmann configuration. We show that the best optimization depends not only on the MO coefficients of ferroma...
Conference Paper
Laser-based technological approaches and methods suitable for volumetric optical recording of digital information and creation of images by formation of different kinds of micromarks in the bulk of materials, transparent for a selected laser wavelength, are evaluated and discussed. Along with the analysis of formation of laser-induced parameterized...
Conference Paper
A phenomenon of thermal emission, which is well-known as laser-induced incandescence, is observed when a light-absorbing object is heated up to a temperature of several thousand Kelvin by nanosecond laser pulses. Laser-induced incandescence (LII) of polished carbon surface at different values of ambient air pressure was studied. A decrease in ambie...
Article
Ratios Sr/Ca for natural total strontium and 90Sr/Ca in plants and in the corresponding soil solutions for three experimental lands with the "fuel" ' type of pollution for several plants under natural conditions are determined. These lands with three different types of soil are at the Exclusion Zone of the Chornobyl Nuclear Power Plant. The obtaine...
Article
Surface structures of polycrystalline and monocrystalline samples of chromium were investigated using the following techniques: magnetic force microscopy, scanning tunneling microscopy, and spectral ellipsometric method. Presence of magnetic nanostructure on the surface of polycrystalline chromium has been explained in terms of spin orientation of...
Article
Full-text available
Optical properties of thin gold films evaporated on glass substrates were studied with the method of spectroscopic ellipsometry in both external and internal reflection configurations as well as with the UV–visible absorption spectroscopy. Here, we discussed how ellipsometric functions Psi and Delta in the spectral region of excitation of surface p...
Conference Paper
Full-text available
The paper devoted to the investigation of optical properties of MgxZn1–xO thin films prepared by pulsed laser deposition technique (Magnesium admixture varies from 0 to 12% by weight). Polycrystalline nature of samples with no impurity or secondary phase formation is shown by X-ray diffraction technique. The optical conductivity is calculated based...
Article
Ellipsometric study of different surfaces of CdTe single crystals was carried out at a light wavelength of 632.8 nm. CdTe(llO) crystals with cleaved surfaces after long time storage under ambient air conditions, Cd- and Te-terminated faces of (111) oriented CdTe crystals aged at room temperature in air during different times and samples chemically...
Conference Paper
Photoluminescence and optical properties of the surface functional layer of detector-grade Cl-compensated semiconductor CdTe(111) single crystals modified by chemical etching and nanosecond laser processing have been studied. A bromine-methanol solution was used for polishing etching and nanosecond pulses of the second harmonic of YAG:Nd laser was...
Article
Optical properties and effective dielectric function of nanostructured materials consisting of silver nanoparticles embed in dielectric matrix were studied. Experimental part was performed by means of angular and spectroscopic ellipsometry. Measured angular dependences reveal, that optical conductivity changes from metallic to dielectric with decre...
Article
In this work the possibility of laser overheating of light-absorbing surfaces of bulk carbon samples to incandescent temperatures with the use of a moderate-power Q-switched YAG-Nd3+ laser (wavelength 1064 nm, pulse duration 20 ns, power density 3-10 MW/cm2) was studied. We observed laser-induced incandescence (LII) of carbon surfaces and investiga...
Article
Full-text available
We consider the crystallization of ITO films induced by excited atomic oxygen. Owing to it, transmittance of these films in visible ranges increased by ∼ 20 % and surface impedance dropped from 36 down to 4.6 Ω / □. The treatment temperature (127 °C) was significantly below that of conventional crystallization (320 °C). Application of elastic light...
Article
The aim of this work is to investigate the channels of transfer of Cs and potassium from soil to plants under natural conditions. Different rapidly maturing plants were grown simultaneously at the same experimental sites under natural conditions at the Chornobyl Exclusion Zone. Roots of the plants were side by side in soil. During two seasons, we s...
Article
Two copper mirrors with different surface roughness are studied by means of spectroscopic ellipsometry. It is established that spectral dependences of optical conductivity are qualitatively similar, but shifted along the ordinate, and some of their peaks may be related to light absorption by the surface oxide layer.
Article
Optical properties and morphology of the opposite polar faces of CdTe(111) single crystals subjected to irradiation with nanosecond pulses of the second harmonic of a YAG:Nd laser in a wide range of energy densities have been studied by multiple-angle-of-incidence single-wavelength ellipsometry and atomic force microscopy. The ellipsometric data ha...
Article
It is well known that optical phenomena in metals at IR spectral region are connected with intraband optical transitions and they are analogues of direct electrical conductivity (resistance) at low frequencies. It can be suggested that in case of alternating current flux through an amorphous metallic ribbon in external magnetic field, correlation b...
Article
Full-text available
Optical properties and surface state of semiconductor CdTe crystals subjected to irradiation with nanosecond laser pulses were studied. Ellipsometric parameters ∆ and Ψ were measured on two opposite surfaces of (111) oriented CdTe wafers before. The samples were subjected to polishing chemical etching and laser irradiation with energy densities low...
Article
The ZnO films deposited by reactive magnetron sputtering are investigated. SEM provides information on the composition of the films and enables us to observe the nanostructures. AFM provides information on the roughness and the texture of the surfaces. Fourier transform, photoluminescence and Raman scattering are used for confirmation of appropriat...
Article
Full-text available
Based on the quantum-mechanical theory of scattering, the paper describes interaction between workpiece debris particles and tool wear particles in the contact zone in polishing. It is shown that the forward scattering of debris particles occurs mostly on the debris particles, and the probability of their scattering on wear particles is insignifica...
Article
Full-text available
The effect of surface laser processing on the optical properties and structure of the surface region of (111) oriented CdTe single crystals have been studied by multiple-angle-of-incidence single-wavelength ellipsometry. The measurements were performed both on Cd and Te surfaces of CdTe(111) crystals and morphology was monitored by AFM. CdTe crysta...
Article
The experimental results of research of structural modifications in amorphous magnetic alloys (AMAs) under thermotreatment obtained by angular and spectroellipsometric methods are presented and discussed. The ductile-brittle transition was observed for the ribbons of some 3d-metal-based amorphous alloys. The relationship between the principal angle...
Article
Data on spectral polarimetric measurements in the range of 0.05–0.60 eV are presented, along with calculations on the optical characteristics of the surface layers of ribbons of the amorphous alloy Co59Fe5Ni10Si11B15 before and after thermal annealing in order to determine how the composition of the surface layer changes during this treatment. It i...
Article
A magnetoimpedance effect is observed in Co80–xNixB20 (x = 4, 6, 8, 10, 12) amorphous metal alloy ribbons when an alternating current at frequencies ranging from 1–3000 kHz is passed through samples in an external magnetic field. Spectra of the permittivity and optical conductivity of the surface of ribbons of these alloys are obtained for incident...
Article
The diffraction losses of laser mirrors were determined by using specially designed spectrometer of spatial frequencies. Reflection surface (70 mm diameter) was made by diamond microgrinding, but instead of an ideal plane, the circular phase grating was formed. The Fourier-optics was applied to measure a real shape of flat laser metal mirrors. We a...
Article
We present the experimental results on magnetorefractive effect in ferromagnetic metal-insulator granular films of different compositions (identical metals but different dielectric matrices) with tunnel magnetoresistance. It was found that the magnitude of the magnetorefractive effect rises with increasing of the magnetic field but the effect itsel...
Article
Full-text available
In this work, we use a nanoimprint lithography fabrication technology to create uniformly-oriented and homogenous noble metal nanoparticle arrays with well-controlled size, shape and spacing, which can be the basis platform for the development of Localized Surface Plasmon Resonance (LSPR) sensors for biomolecular detection. Using this approach, we...
Article
Full-text available
The maximization of the sensitivity of magneto-optical recording media in the short wavelength region is discussed. We show that a combination of the optimized thickness of dielectric and Ag (or CoAg) films can increase the magneto-optic Kerr effect in FeTbCo media by about five times of magnitude in the UV and blue spectral range. It has been show...
Article
Full-text available
This work deals with application of Kramers-Kronig transform method for optical constants and electron characteristic determination for Fe-based amorphous alloys in wide spectral range. The parameters of the specimens, analyzed, were obtained with relatively high accuracy allowing plasma frequency determination. A reliable correlation of plasma fre...
Article
Full-text available
In this work, we investigate how the application of an external potential difference to the sensitive gold-electrolyte interface influences the optical response of a sensor based on the surface plasmon-polariton resonance (SPPR). The SPPR resonant angle shift was registered for an aqueous solution of sulfuric acid as an electrolyte at different pot...
Conference Paper
Full-text available
The conference paper is dedicated to determination of Kramers-Kronig transform accuracy and application for analysis of Fe-based amorphous and crystallized alloys, including determination of plasmon frequency. Substituting 5% of Fe atoms by an 3d-element prior to Fe in periodic table does not significantly alter intensity of interband transitions,...
Conference Paper
Full-text available
IR ellipsometric studies has revealed that treatment of the polycrystalline Ti surface e by the mixed Ti+ and C+ ion beam caused much stronger changes of its subsurface optical properties that treatment of polycrystalline Mo by the same ion beam. A set of crystallized and amorphous alloys of Fe80TM5B15 type, where TM is an element of 3d transition...
Conference Paper
Full-text available
The modification of Kramers-Kronig transform form allows removing integrand singularity and increasing accuracy by an order on the experimental range edges comparing to the classic approach. The use of open quadrature method for numerical integration allows accuracy increase up to 50%. The integration of log-linear extrapolations by Taylor series e...
Conference Paper
Full-text available
IR ellipsometric studies has revealed that treatment of the polycrystalline Ti surface e by the mixed Ti+ and C+ ion beam caused much stronger changes of its subsurface optical properties that treatment of polycrystalline Mo by the same ion beam, because the bombarding ions (Ti+) have an affinity with Ti surface atoms. The treatment resulted in for...
Article
The light reflection spectra and the magnetorefractive effect in the cobalt-based amorphous ribbons in the IR spectral region (λ = 2.5–25 μm) are studied. These amorphous alloys are characterized by the magnetoimpedance effect, which is enhanced after thermal and laser annealing. It is found that the magnetoimpedance and magnetorefractive effects c...
Article
Full-text available
The room temperature ferromagnetism is observed in chemically synthesized powderlike samples of Sn1−xCoxO2 compound (x = 0.07 and 0.1). The Raman spectra of the Sn1−xCoxO2 films were analyzed in terms of their structural and magnetic properties. In the Raman spectra of the Sn1−xCoxO2 films additional features were revealed which are associated with...
Article
The structural, optical, and magnetooptical properties of Co-SiO2 granular films are studied. It is found that the magnetooptical response is considerably enhanced in samples with a metal component concentration close to the percolation threshold. The Co nanogranules formed in the SiO2 matrix exhibit ferromagnetic properties and are ordered into th...
Article
Optical properties of thin TiAlSiN-based films are investigated by the Beattie spectroellipsometric method before and after annealing. The dispersion dependences of the optical conductivity σ, the real part of the dielectric function ε 1, and the energy reflection coefficient R at the normal angle of light incidence are obtained for the films at ro...
Article
We investigate the optical properties of Cu-Fe alloys in a wide interval of concentrations (7.5–30 at. %) and in a wide spectral interval (0.25–7 µm). An additional absorption associated with interband electron transitions from localized states of impurities to the Fermi level has been revealed in the 0.98–1.9-eV spectral range. The energy bands in...
Article
Full-text available
The systems "thin Ni film – lithium niobate" and "thin Pd film – lithium tantalate" are implanted by Ar + ions with an energy of 100 keV and a dose of 10 16 cm -2 . Analyses of the systems by AFM and SEM have shown that the ion implantation essentially modifies the near-surface structure resulting in a change of its optical, electrical, and mechani...
Article
Full-text available
The approach described in the present paper was applied for analysis of Fe-based amorphous and crystallized alloys. All the analyzed specimens have Sw~1. Using classical approach to the Kramers-Kronig transform this value is insufficient for refraction index and therefore optical conductivity determination. The present paper considers new ways of K...
Chapter
The spectral dependence of photolurninescence and optical conductivity for the solid C-60 and Cd-C-60 films (with the admixture Of C-70 fullerenes) are studied under irradiation by argon ions with different doses. The fragmentation of the C60 molecules and the formation of the radiation defects, which are accompanied by appearance and increase in t...