Alex Ulyanenkov

Atomicus GmbH

In the present paper we show that the Hamiltonian describing the resonant interaction of $N$ two-level systems with a single-mode electromagnetic quantum field in the Coulomb gauge can be diagonalized with a high degree of accuracy using a simple basis set of states. This allows one to find an analytical approximation for the eigenvectors and eigen...

In the present paper we show that the Hamiltonian describing the resonant interaction of $N$ two-level systems with a single-mode electromagnetic quantum field in the Coulomb gauge can be diagonalized with a high degree of accuracy using a simple basis set of states. This allows one to find an analytical approximation for the eigenvectors and eigen...

Fisher information is a powerful mathematical tool suitable for quantification of data ‘informativity’ and optimization of the experimental setup and measurement conditions. Here, it is applied to X-ray diffraction and an informational approach to choosing the optimal measurement configuration is proposed. The core idea is maximization of the infor...

Identification of mass-spectrum peaks is an indispensable step of an atom-probe tomography reconstruction process and can be a time-consuming procedure, vulnerable to errors, if performed manually. We propose a Bayesian approach to the peak identification problem, based on ranking of candidate ions according to their calculated posterior probabilit...

An approach to visualize the accessible reciprocal space accounting the goniometer angles limitation and the resolution element in the reciprocal space is presented. The shapes of the accessible reciprocal space region for coplanar and non-coplanar geometries are given employing the additional degree of freedom provided by detector arm. The example...

The structural characterization of multilayer thin coatings is performed by X-ray diffraction using a noncoplanar measurement geometry. The application of such a measurement geometry enables a reliable and comprehensive microstructural analysis of the material comparing to other measurement geometries due to the accessibility to a larger number of...

The development of structural materials for nuclear application is of great importance. Along with it, the development of radiation tolerant coatings for the application in reactors is of no less importance [1]. One of the kinds of such protective coatings that often used is nitride-based ceramics due to their specific combination of properties sui...

Parametric X-ray radiation (PXR) from relativistic electrons moving in a crystal along the crystal-vacuum interface is considered. In this geometry the emission of photons is happening in the regime of extremely asymmetric diffraction (EAD). In the EAD case the whole crystal length contributes to the formation of X-ray radiation opposed to Laue and...

The experimental x-ray diffraction patterns of a Si$_{0.4}$Ge$_{0.6}$/Si(001) epitaxial film with a low density of misfit dislocations are modeled by the Monte Carlo method. It is shown that an inhomogeneous distribution of 60$^\circ$ dislocations with dislocations arranged in bunches is needed to explain the experiment correctly. As a result of th...

The experimental x-ray diffraction patterns of a Si$_{0.4}$Ge$_{0.6}$/Si(001) epitaxial film with a low density of misfit dislocations are modeled by the Monte Carlo method. It is shown that an inhomogeneous distribution of 60$^\circ$ dislocations with dislocations arranged in bunches is needed to explain the experiment correctly. As a result of th...

Identification of unknown materials using X-ray powder diffraction patterns is a commonly used and well established technique with a number of proved implementations. Generally, qualitative phase analysis of X-ray diffraction data includes ranking of candidate phases on the basis of similarity of their diffraction patterns to the measured one. A st...

Diffraction in multilayers in the presence of interfacial roughness is studied theoretically, the roughness being considered as a transition layer. Exact (within the framework of the two-beam dynamical diffraction theory) differential equations for field amplitudes in a crystalline structure with varying properties along its surface normal are obta...

The extended analysis of various physical problems related to anharmonic oscillator performed in previous chapter makes it possible to sort out the capabilities of the operator method, which are not exclusively related to QAO and can be exploited for description of more complex quantum systems.

The essential achievements in modern quantum theory are closely connected to the microscopic description of many-electron systems in quantum chemistry, biology and condensed matter physics by using density functional theory (DFT), introduced in pioneering works [1, 2]. This approach is used as a basis for ab initio calculations for complex molecula...

The multi-dimensional physical systems with low number of the degrees of freedom take a special place in the development of new analytical and approximate methods for theoretical physics. The approaches used for the systems with the large number of the degrees of freedom and applied to the statistical physics and to the theory of the quantum field...

A two-dimensional exciton in a magnetic field has been of great interest to both theoretical and experimental researchers for many years [1–3] and continues to be after several new and interesting physical effects discovered in recent years [4–7]. The energy spectrum and wave function of exciton in magnetic field, therefore, need to be calculated w...

The majority of physical phenomena in condensed matter, atomic and molecular systems is defined by electromagnetic interactions and governed by quantum mechanics laws. The systems possess an entirely defined Hamiltonian and the physical properties are described by the corresponding solutions of Schrödinger equation. The quantum description has an u...

The construction of the uniformly available approximation (UAA) for thermodynamical functions has two specific features, which differ it from the solution of the Schrödinger equation for stationary states. First of all, these functions depend both on Hamiltonian parameters and on the temperature T.

This chapter is dedicated to the applications of operator method for the analysis of propagation of electron in ionic crystal, called often as propagation of polaron of a large radius. This task is qualitatively distinguishable from the ones discussed in previous chapters by the fact that Hamiltonian includes the interaction of electron with the sy...

Modeling of the X-ray diffractometer instrumental function for a given optics configuration is important both for planning experiments and for the analysis of measured data. A fast and universal method for instrumental function simulation, suitable for fully automated computer realization and describing both coplanar and noncoplanar measurement geo...

The component approximation method for the reconstruction of orientation distribution function (ODF) is based on the assumption that the texture could be presented as a weighted linear combination of distributions depending on the parameters, which are related to the position of bell shaped function in orientation space and to the dispersion. The m...

Strained germanium grown on silicon with nonstandard surface orientations like (011) or (111) is a promising material for various semiconductor applications, for example complementary metal-oxide semiconductor transistors. However, because of the large mismatch between the lattice constants of silicon and germanium, the growth of such systems is ch...

Highly boron doped epitaxial silicon, with boron concentrations well above 1x10 ²⁰ cm ‐3 , is of great interest for applications in large variety of electronic and photonic devices where it is used as a low resistivity contact. The Bragg peak position of a homogeneous solid solution epitaxial film is directly related to the solid solution concentra...

This book introduces systematically the operator method for the solution of the Schrödinger equation. This method permits to describe the states of quantum systems in the entire range of parameters of Hamiltonian with a predefined accuracy. The operator method is unique compared with other non-perturbative methods due to its ability to deliver in z...

In this chapter, the operator method is applied to analyze the following models intensively used for the description of the interaction of atomic systems with external fields: (1) hydrogen-like atom in electric and magnetic fields, and (2) two-level atom in resonant electromagnetic field. Hydrogen-like atom in electric field or/and in magnetic fiel...

The majority of approximate methods for the solution of Schrödinger equation (SE) demonstrated in Chap. 1 is not sufficiently universal and theirs applications in the case of system with many degrees of freedom are bound up with serious difficulties. In the following chapters we consider the method which is proposed as an universal procedure for tr...

A methodology is presented to characterize residual stress gradients using the sin²ψ technique at constant penetration depths without the use of sample χ tilting. The experiments were performed using a laboratory five-axis X-ray diffractometer equipped with an in-plane arm by scanning several reflections in order to enlarge the penetration depth ra...

The reflection phenomena, discussed in the previous chapter, are inherent for radiation of arbitrary wavelength.

Nowadays the X-rays are widely used for non-destructive quantitative and qualitative characterization of the materials used in modern electronics, optics, semiconductor industry, lasers, sensors, and many other applications on micro- and nano-level.

X-ray residual stress analysis is a widespread nondestructive technique to investigate the residual stress and residual stress gradient in thin films and protective coatings.In the present contribution we introduce a new method based on the noncomplanar measurement geometry that allow to span large area of sin2 ψ and penetration depth values withou...

Oxide dispersive steel is a promising material for next nuclear reactors generation. Performance of this material in nuclear reactor can be modeled by means of irradiation by swift Bi ions, which are typical nuclear fusion products. Radiation damage results in microstructure alternation leading to formation of micro and macro stresses that influenc...

A noncoplanar measurement geometry, achieved by using a diffractometer equipped with a detector arm possessing two degrees of freedom, is a promising technique for the analysis of residual stress gradients in polycrystalline objects and for anisotropic microstructure investigations. The instrumental function for a parallel beam and a set of two ort...

In the Chap. 2, the description of the interaction of X-ray radiation with media (X-ray optics) has been shown to be based on the solution of wave equation (2.2)

In the Chap.4, the X-ray diffraction from perfect crystals has been considered in details, however, the real crystals always posses the defects.

The general calculation of the scattered from the sample X-ray intensity requires the solution of the Eq. (2.1). However, the geometry of the experiment has to be also taken into account, because of the mutual arrangement of the X-ray source, the sample and the detector as well as the shape of the sample influence the observed results.

In the previous chapters, the X-ray analysis has been applied to the samples with the electron density distributed uniformly in a macroscopic volume: the constant value for XRR analysis and three-dimensional periodic function in case of HRXRD analysis.

Microscopic analysis of various processes arising due to the interaction of X-rays with condensed matter was considered in many papers, especially in the fundamental monograph [1], where the basic principles of X-ray optics were described. However, since that time a series of advanced techniques for X-ray structure characterization have been active...

The Bragg peak position of a homogeneous solid solution epitaxial film is directly related to the solid solution concentration, film strain and, consequently, residual stress. The peak shape contains information about defects present in the sample. In the case of compositionally graded epitaxial films the situation is more complex since instead of...

The technique of reciprocal space mapping using X-rays is a recognized tool for the nondestructive characterization of epitaxial films. X-ray scattering from epitaxial Si0.4Ge0.6 films on Si(100) substrates using a laboratory X-ray source was investigated. It is shown that a laboratory source with a rotating anode makes it possible to investigate t...

A general theoretical approach to the description of epitaxial layers with essentially different cell parameters and in-plane relaxation anisotropy has been developed. A covariant description of relaxation in such structures has been introduced. An iteration method for evaluation of these parameters on the basis of the diffraction data set has been...

This book provides a concise survey of modern theoretical concepts of X-ray materials analysis. The principle features of the book are: basics of X-ray scattering, interaction between X-rays and matter and new theoretical concepts of X-ray scattering. The various X-ray techniques are considered in detail: high-resolution X-ray diffraction, X-ray re...

The self-assembled iron oxide nanoparticles synthesized by a high-temperature solution phase reaction and the silicon dots produced by an ion bombardment have been investigated by using atomic force microscopy (AFM) and grazing-incidence small-angle scattering (GISAXS) technique. Both methods delivered the consistent results on the estimate for the...

The series of samples is investigated to verify the validity of the scattering theory within the layers of different relaxation degree. The samples composed of In0.06Ga0.94As layer of different thicknesses on GaAs [001] substrates were grown using MBE technique. The symmetric and asymmetric reciprocal space maps (RSM) were measured and simulated fo...

Epitaxially grown silicon germanium alloy layers, prepared as virtual substrates for modulation-doped field effect transistors, and InxGa1−xAs and GaPxAs1−x graded layers on GaAs substrates prepared as distributed Bragg reflectors (DBRs), have been investigated by the reciprocal space mapping (RSM) technique. These structures possess a strong conce...

This work presents a detailed characterization, using high-resolution x-ray diffraction, of multilayered Si _1-x Ge _x heterostructures grown on (001), (011), and (111) Si substrates by reduced pressure chemical vapor deposition. Reciprocal space mapping has been used to determine both the strain and Ge concentration depth profi...

A method is proposed to determine the concentration and relaxation depth profiles in graded epitaxial films from x-ray reciprocal space maps (RSMs). Various approximations in the kinematical x-ray diffraction from epitaxial films with the misfit dislocation density depth profile are developed. We show that a symmetric and an asymmetric RSM, or two...

Roughness influence on the residual stress gradient evaluation in the case of a grazing incidence X-ray diffraction setup is considered. In this geometry the surface roughness changes essentially the X-ray wave fields of the transmitted and diffracted beams inside the coatings and subsurface regions of bulk samples, and thus influences the refracti...

In the presence of texture, the concept of X-ray elastic constants as well as Sin2ψ law is inapplicable and the X-ray stress factors (XSF) connecting average strain and stress have to be used [1-2]. The SO(3) vector parameterization with smart composition law [3-4] proved to be a powerful tool for handling transformations between reference systems...

Residual Stress measurement as routine industrial application

Poster