Uzhhorod National University

About: Uzhhorod National University is a education organization based out in Uzhhorod, Ukraine. It is known for research contribution in the topics: Raman spectroscopy & Laser. The organization has 1089 authors who have published 1056 publications receiving 5187 citations. The organization is also known as: State Higher Education Establishment "Uzhhorod National University" & Uzhhorod State University.

Reconstruction of bi-dimensional images in Fourier-transform acousto-optic imaging.

Abstract: We present a new, to the best of our knowledge, method to perform acousto-optic imaging based on a spatiotemporal structuration of long-duration acoustic plane waves. This approach is particularly relevant when using detectors with long integration times. We show how it is possible to reconstruct an image by measuring its two-dimensional Fourier components. A proof of concept is presented using a photorefractive detection scheme, demonstrating equal performances to direct imaging. The overall acquisition time is compatible with medical monitoring applications.

Quasiclassical Study of the Quantum Mechanical Two-Coulomb-Centre Problem

Abstract: A recurrent scheme for finding the quasiclassical solutions of the onedimensional equation got by the separation of variables from the Schrodinger equation in prolate spheroidal coordinates has been elaborated. By means of this scheme, WKB expansion quasiclassical two-Coulomb-centre wave functions at large distances between the fixed positive charges (nuclei) have been constructed for the entire space of the negative particle (electron). Our method provides simple uniform estimates of the eigenfunctions at arbitrary internuclear distances R, R ≫ 1 included. In contrast to the perturbation theory, the interaction need not be very small in the quasiclassical approximation. Its applicability domain is hence wider. That permits analyzing qualitative laws for the behavior and properties of quantum mechanical systems.

Spectrometric and ellipsometric studies of (1 − x)TiO2 · xLn2O3 (Ln = Nd, Sm, Gd, Er, Yb) thin films

Abstract: Spectrometric and ellipsometric studies of (1 − x)TiO2 · xLn2O3 (Ln = Nd, Sm, Gd, Er, Yb; x = 0.33, 0.5) thin films at room temperature were performed. The obtained dispersion dependences of refractive indices are successfully described by the optical-refractometric relation. The dependence of optical pseudogap and refractive indices on composition and molar mass of the films is investigated. The influence of compositional disordering on the energy width of the exponential absorption edge is studied.

Electric Properties of Lithium Tetraborate in Vitreous and Crystalline States

Abstract: The results of the studies of temperature-frequency dependences of electric properties of Li 2 B 4 O 7 compound in the crystalline and vitreous states within the temperature range from room temperature to 1100 K and frequency range from 0.001 to 1.0 MHz are presented. The analysis of the dominating ionic conductivity is performed within the framework of the model of dielectric cation relaxation in the intersite positions along the conduction channels. The minimal leap length of the Li + cations and the potential barrier height between their adjacent positions are determined. The obtained parameters are compared with the results of the structural studies.

Quadrilateral quantum chain hamiltonian cast in positive semidefinite form containing non-linear fermionic contributions

Abstract: The transformation of a Hamiltonian (connected to a quantum mechanical many-body system) in positive semidefinite form represents an important procedure in a powerful tool used in deducing exact results for nonintegrable systems. Motivated by this fact, we report in this paper the exact transformation of a Hubbard type of Hamiltonian (describing in the presented case an itinerant fermionic quadrilateral chain) in positive semidefinite form, in a such a way that the kinetic and interaction energy terms of the Hamiltonian are treated similarly together, and are provided by the same positive semidefinite expression. For this reason, non-linear fermionic contributions are used in block operators from which the positive semidefinite forms are constructed. The transformation is possible to be done when a system of nonlinear equations, called matching equations, are satisfied. The procedure of solving the matching equations is also indicated. Key–Words:Non-integrable many-body systems, Hamiltonian in positive semidefinite form, exact ground states