Inductive effect of crystalline nucleus on the structure of its local environment in the process of quartz glass crystallization

Проведено исследование электронного строения 6,6 - дифторундекана (6,6 - FCH) и структурных изомеров к, к-дифтороктана (к, к-FCH, где 1 ≤ к ≤ 8, к - положение фторов в углеводородной цепи). В рамках «квантовой теории атомов в молекулах» найдены переносимые или «стандартные» электронные параметры топологических атомов и атомных групп (заряд, объем и энергия). Оценена дальность индуктивного воздействия атомов фтора и фторсодержащих фрагментов (CHF и CF) на ближайшее окружение. Установлено, что влияние CHF распространяется на четыре CH , а CF на две CH группы в обе стороны по алкильной цепи. Получены данные по изменениям электронных параметров в зависимости от удаления от атома фтора. Составлен ряд групповых электроотрицательностей, согласно которому CF является более сильным акцептором электронной плотности, чем CHF. The investigation of the electronic structure of the 6,6 - difluorine undecane (6,6 - FCH ) and structural isomers of к, к - difluorine octane molecules (к, к-FCH, 1 ≤ к ≤ 8, where к is a position of the fluorine atoms in alkyl chain) has been carried out. Within the «quantum theory of atoms in molecules» the transferable or «standard» electron parameters of topological atoms and atomic groups (charge, energy and volume) have been determined. The inductive effect spread from the fluorine and the fluorine-containing fragments (CHF and CF) on local environment was explored. The influence of CHF applies to four CH groups along the hydrocarbon chain, the influence of CF applies to two CH groups in both sides along the hydrocarbon chain. Data on changes in electronic parameters depending on the distance from the fluorine atom were obtained. Series of electronegativity of the functional groups has been made up. According to it CF group is a stronger acceptor of electron density, than CHF.

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Confocal Raman spectroscopy of island nuclei formed at the initial stage of quartz glass crystallization

Optics and Spectroscopy ◽

10.1134/s0030400x16120201 ◽

2016 ◽

Vol 121 (6) ◽

pp. 831-836

Author(s):

D. V. Pankin ◽

V. M. Zolotarev ◽

M. Colas ◽

J. Cornette ◽

M. G. Evdokimova

Keyword(s):

Raman Spectroscopy ◽

Quartz Glass ◽

Glass Crystallization ◽

Confocal Raman Spectroscopy ◽

Initial Stage ◽

Confocal Raman

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Mössbauer spectroscopy study of 60P2O5-40Fe2O3 glass crystallization

Nukleonika ◽

10.1515/nuka-2015-0028 ◽

2015 ◽

Vol 60 (1) ◽

pp. 133-136 ◽

Cited By ~ 6

Author(s):

Paweł Stoch ◽

Agata Stoch

Keyword(s):

Heat Treatment ◽

Mössbauer Spectroscopy ◽

Structural Changes ◽

Mossbauer Spectroscopy ◽

Local Environment ◽

Iron Ions ◽

Spectroscopy Study ◽

Glass Crystallization ◽

Octahedral Sites ◽

Mößbauer Spectroscopy

Abstract 60P2O5-40Fe2O3 glass was synthesized and 57Fe Mössbauer spectroscopy study was presented. The main goal of the research was to investigate structural changes of local environment of iron ions during gradual crystallization of the glass. It was observed that some changes were evidenced at temperature of heat treatment higher than 400°C, above which content of tetrahedrally coordinated Fe3+ was increased in cost of octahedral sites. This led to formation of areas of nucleation of α-FePO4. Crystallization of α-Fe3(P2O7)2 and Fe2P2O7 was also observed.

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Residual Gas Reaction in the Electron Microscope: II The Design of a Gas-Control Chamber for Quantitative Observations

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100062324 ◽

1969 ◽

Vol 27 ◽

pp. 82-83

Author(s):

Chester J. Calbick ◽

Richard E. Hartman

Keyword(s):

Electron Beam ◽

Electron Microscope ◽

Local Environment ◽

Chamber Pressure ◽

Objective Lens ◽

Ion Pump ◽

Quantitative Studies ◽

Precise Knowledge ◽

Differential Pumping ◽

And Control

Quantitative studies of the phenomenon associated with reactions induced by the electron beam between specimens and gases present in the electron microscope require precise knowledge and control of the local environment experienced by the portion of the specimen in the electron beam. Because of outgassing phenomena, the environment at the irradiated portion of the specimen is very different from that in any place where gas pressures and compositions can be measured. We have found that differential pumping of the specimen chamber by a 4" Orb-Ion pump, following roughing by a zeolite sorption pump, can produce a specimen-chamber pressure 100- to 1000-fold less than that in the region below the objective lens.

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An emerging technology: Nuclear magnetic resonance microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010010706x ◽

1988 ◽

Vol 46 ◽

pp. 1000-1001

Author(s):

M.J. Hennessy ◽

E. Kwok

Keyword(s):

Nuclear Magnetic Resonance ◽

Magnetic Resonance ◽

Relaxation Times ◽

Basic Research ◽

Local Environment ◽

Magnetic Resonance Images ◽

Nmr Microscopy ◽

Mri Scans ◽

Temperature Relaxation ◽

Nuclear Magnetic

Much progress in nuclear magnetic resonance microscope has been made in the last few years as a result of improved instrumentation and techniques being made available through basic research in magnetic resonance imaging (MRI) technologies for medicine. Nuclear magnetic resonance (NMR) was first observed in the hydrogen nucleus in water by Bloch, Purcell and Pound over 40 years ago. Today, in medicine, virtually all commercial MRI scans are made of water bound in tissue. This is also true for NMR microscopy, which has focussed mainly on biological applications. The reason water is the favored molecule for NMR is because water is,the most abundant molecule in biology. It is also the most NMR sensitive having the largest nuclear magnetic moment and having reasonable room temperature relaxation times (from 10 ms to 3 sec). The contrast seen in magnetic resonance images is due mostly to distribution of water relaxation times in sample which are extremely sensitive to the local environment.

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Electron energy-loss near-edge structure in silicate minerals

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100130924 ◽

1992 ◽

Vol 50 (2) ◽

pp. 1258-1259

Author(s):

D W McComb ◽

R S Payne ◽

P L Hansen ◽

R Brydson

Keyword(s):

Solid State ◽

Energy Loss ◽

Electron Energy ◽

State Energy ◽

Local Environment ◽

Edge Structure ◽

Silicate Minerals ◽

Two Samples ◽

Electron Energy Loss ◽

Careful Processing

Electron energy-loss near-edge structure (ELNES) is an effective probe of the local geometrical and electronic environment around particular atomic species in the solid state. Energy-loss spectra from several silicate minerals were mostly acquired using a VG HB501 STEM fitted with a parallel detector. Typically a collection angle of ≈8mrad was used, and an energy resolution of ≈0.5eV was achieved.Other authors have indicated that the ELNES of the Si L2,3-edge in α-quartz is dominated by the local environment of the silicon atom i.e. the SiO4 tetrahedron. On this basis, and from results on other minerals, the concept of a coordination fingerprint for certain atoms in minerals has been proposed. The concept is useful in some cases, illustrated here using results from a study of the Al2SiO5 polymorphs (Fig.l). The Al L2,3-edge of kyanite, which contains only 6-coordinate Al, is easily distinguished from andalusite (5- & 6-coordinate Al) and sillimanite (4- & 6-coordinate Al). At the Al K-edge even the latter two samples exhibit differences; with careful processing, the fingerprint for 4-, 5- and 6-coordinate aluminium may be obtained.

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