scholarly journals DEPENDENCE OF ELASTIC STRESSES ON THE THICKNESS OF THE DEPOSITED MATERIAL FOR GERMANIUM GROWTH ON SILICON

2020 ◽  
Author(s):  
Andrey Kokhanenko ◽  
Vladimir Dirko ◽  
Kiril Lozovoy
Keyword(s):  
Quantum Dots ◽  
Electron Diffraction ◽  
Fast Electron ◽  
Diffraction Method ◽  
Elastic Stresses ◽  
Relative Value ◽  
Germanium Quantum Dots

In this work, the dependences of the elastic stresses on the thickness of the deposited material during the growth of germanium quantum dots on silicon have been determined by the fast electron diffraction method. It is shown that the relative value substrate in this system reaches 12.5%.

scholarly journals Структура межфазной границы alpha-beta в твердом растворе PdCu

2020 ◽  
Vol 62 (1) ◽  
pp. 53
Author(s):  
В.М. Иевлев ◽  
А.С. Прижимов ◽  
А.И. Донцов
Keyword(s):  
Molecular Dynamics ◽  
Solid Solution ◽  
Electron Diffraction ◽  
Fast Electron ◽  
Diffraction Method ◽  
Orientation Relation ◽  
Β Phase ◽  
Phase Coordinates ◽  
Interfacial Dislocations ◽  
Alpha Beta

In accordance with the orientation relation (110),<001>β || (111),<110> α, established by the fast electron diffraction method between ordered (β) and disordered (α) phases in the Pd – 57 at .% Cu solid solution foil , the atomic structure of the interface is modeled by molecular dynamics. It is found that the structural and dimensional mismatch is compensated by interfacial dislocations with Burgers vectors a / 2 <111> in β-phase coordinates.

Three-phase structure invariants and structure factors determined with the quantitative convergent-beam electron diffraction method

1999 ◽  
Vol 55 (2) ◽  
pp. 188-196 ◽  
Author(s):  
R. Høier ◽  
C. R. Birkeland ◽  
R. Holmestad ◽  
K Marthinsen
Keyword(s):  
Electron Diffraction ◽  
Phase Structure ◽  
Diffraction Method ◽  
Convergent Beam Electron Diffraction ◽  
Beam Electron ◽  
Structure Factors ◽  
Refinement Method ◽  
Three Phase ◽  
Phase Sensitive ◽  
Convergent Beam

Quantitative convergent-beam electron diffraction is used to determine structure factors and three-phase structure invariants. The refinements are based on centre-disc intensities only. An algorithm for parameter-sensitive pixel sampling of experimental intensities is implemented in the refinement procedure to increase sensitivity and computer speed. Typical three-beam effects are illustrated for the centrosymmetric case. The modified refinement method is applied to determine amplitudes and three-phase structure invariants in noncentrosymmetric InP. The accuracy of the results is shown to depend on the choice of the initial parameters in the refinement. Even unrealistic starting assumptions and incorrect temperature factor lead to stable results for the structure invariant. The examples show that the accuracy varies from 1 to 10° in the electron three-phase invariants determined and from 0.5 to 5% for the amplitudes. Individual phases could not be determined in the present case owing to spatial intensity correlations between phase-sensitive pixels. However, for the three-phase structure invariant, stable solutions were found.

New electron diffraction method to identify the chirality of enantiomorphic crystals

2003 ◽  
Vol 59 (6) ◽  
pp. 802-810 ◽  
Author(s):  
Haruyuki Inui ◽  
Akihiro Fujii ◽  
Katsushi Tanaka ◽  
Hiroki Sakamoto ◽  
Kazuo Ishizuka
Keyword(s):  
Electron Diffraction ◽  
Multiple Scattering ◽  
Present Method ◽  
Diffraction Method ◽  
Convergent Beam Electron Diffraction ◽  
Intensity Difference ◽  
Crystal Thickness ◽  
Dynamical Nature ◽  
Convergent Beam ◽  
Phase Angles

A new CBED (convergent-beam electron diffraction) method is proposed for the identification of the chirality of enantiomorphic crystals, in which asymmetry in the intensity of the reflections of Bijvoet pairs in an experimental symmetrical zone-axis CBED pattern is compared with that of a computer-simulated CBED pattern. The intensity difference for reflections of these Bijvoet pairs results from multiple scattering (dynamical nature of electron diffraction) among relevant Bijvoet pairs of reflections, each pair of which has identical amplitude and different phase angles. Therefore, the crystal thickness where chiral identification is made with the present method is limited by the extinction distance of Bijvoet pairs of reflections relevant to multiple scattering to produce the intensity asymmetry, which is usually of the order of a few tens of nanometers. With the present method, a single CBED pattern is sufficient and chiral identification can be made for all the possible enantiomorphic crystals that are allowed to exist in crystallography.

Molecular structure study of 1,2,3-trimethyldiaziridine by means of gas electron diffraction method

2018 ◽  
Vol 30 (2) ◽  
pp. 457-464 ◽  
Author(s):  
Ilya I. Marochkin ◽  
Vladimir V. Kuznetsov ◽  
Anatolii N. Rykov ◽  
Nina N. Makhova ◽  
Igor F. Shishkov
Keyword(s):  
Molecular Structure ◽  
Electron Diffraction ◽  
Diffraction Method ◽  
Structure Study ◽  
Gas Electron Diffraction

scholarly journals Molecular Structure of Pyrazinamide: a Critical Assessment of Modern Gas Electron Diffraction Data from Three Laboratories

2020 ◽  
Author(s):  
Arseniy A. Otlyotov ◽  
Georgiy V. Girichev ◽  
Anatolii N. Rykov ◽  
Timo Glodde ◽  
Yury Vishnevskiy
Keyword(s):  
Molecular Structure ◽  
Electron Diffraction ◽  
Structure Refinement ◽  
Diffraction Method ◽  
Detailed Examination ◽  
Gas Electron Diffraction ◽  
Electron Diffraction Data ◽  
Data Sets ◽  
Background Elimination ◽  
Diffraction Patterns

<div><div>Accuracy and precision of molecular parameters determined by modern gas electron diffraction method</div><div>have been investigated. Diffraction patterns of gaseous pyrazinamide have been measured independently in three laboratories, in Bielefeld (Germany), Ivanovo (Russia) and Moscow (Russia). All data sets have been analysed in equal manner using highly controlled background elimination procedure and flexible restraints in molecular structure refinement. In detailed examination and comparison of the obtained results we have determined the average experimental precision of 0.004 Å for bond lengths and 0.2 degrees for angles. The corresponding average deviations of the refined parameters from the ae-CCSD(T)/ccpwCVTZ theoretical values were 0.003 Å and 0.2 degrees. The average precision for refined amplitudes of interatomic vibrations was determined to be 0.005 Å. It is recommended to take into account these values in calculations of total errors for refined parameters of other molecules with comparable complexity.</div></div><div><br></div>

scholarly journals Synthesis, Surface Modification and Purification of Silicon and Germanium Quantum Dots for Biological Applications

2021 ◽  
Author(s):  
◽  
Amane Shiohara
Keyword(s):  
Quantum Dots ◽  
Optical Properties ◽  
Silica Nanoparticles ◽  
Microemulsion System ◽  
Biological Applications ◽  
Silicon Quantum Dots ◽  
Surface Molecules ◽  
Silicon And Germanium ◽  
Germanium Quantum Dots ◽  
Oxygen Atoms

<p>Quantum dots have applications in biomedical fields such as bio-imaging and drug delivery systems. This thesis describes research on silicon and germanium nanoparticles (quantum dots) synthesis and surface modification for biological applications. Purification methods of these quantum dots were also explored. In chapter 6 the application of silica nanoparticles into dry eye diagnosis was studied. The purpose of this research is to contribute the application of nanotechnology into biological fields. The crystalinity of the quantum dots was characterised by Transmission Electron Microscopy (TEM) and Selected Area Electron Diffraction analysis (SAED). The molecules on the surface of the quantum dots were characterised by Fourier Transform Infrared spectroscopy (FTIR) and Nuclear Magnetic Resonance (NMR).  Silicon quantum dots were synthesised with a microemulsion system and various types of molecules were attached on the surface of the silicon quantum dots. However, some of the capping molecules which have oxygen atoms tend to form bonds between oxygen and silicon. Therefore, in the later chapter (chapter 4) various chemical reactions were conducted on the molecules attached to the silicon quantum dots. The silicon quantum dots were capped with diene molecules and one of the double bonds was left on the terminal end. The terminal end double bonds were converted to the functional groups which contain oxygen atoms to form peptide bonds. In this way it was confirmed that it can reduce the risk of oxygen atoms to be attached on the surface of the silicon quantum dots. The molecules on the surface of the silicon quantum dots were characterised mainly by FTIR and ¹H NMR. Optical properties and cyto-toxicity of these silicon quantum dots were also measured and analysed depending on the surface molecules.  Two synthetic approaches were taken to produce germanium quantum dots. The first approach was the microemulsion system at room temperature. Different combinations of the surfactant and capping molecules were tested. For the second approach, high temperature bench top system was applied. In this method the bio-friendly molecules which have high boiling points were chosen as capping agents. The surface molecules were characterised by FTIR spectroscopy.  In chapter 6 the synthesis of dye molecules conjugated silica nanoparticles was described. The purpose of this research is to produce biologically safe nanoparticles which can be applied in dry eye diagnosis. Three different dyes were used to conjugate with the silica nanoparticles. Only fluorescein isothiocyanate (FITC) succeeded in conjugating with the nanoparticles. Optical properties of this sample were measured and compared with the free dye molecule. Also the sample was applied in human eyes to analyse the tear film layer.  An overall conclusion and future plans for the research were given in the last chapter.In this chapter, ideas of overcoming the problems and improving the techniques conducted in the research were described.</p>

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