Vladimir Chizhik

Vladimir Chizhik
Saint Petersburg State University | SPBU · Faculty of Physics

Doctor of Science

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109
Publications
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616
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Publications

Publications (109)
Article
Full-text available
Previous works showed a significant increase in the rotational correlation time of the water bound to the hemoglobin S during the aggregation process under sickle cell disease. In this case, the contribution of "Curie-Spin" relaxation mechanism to proton relaxation may be expected. The Curie-Spin relaxation mechanism has been well described theoret...
Article
Full-text available
The low signal-to-noise ratio is a characteristic feature of NMR experiments in the Earth’s magnetic field. The main problem of such studies is the ineffectiveness of signal accumulation due to fluctuations of the Earth’s magnetic field because of magnetic interferences from laboratory equipment and other magnetic field sources. Taking into account...
Article
Full-text available
The 1H-13C cross-polarization (CP) kinetics in poly[2-(methacryloyloxy)ethyltrimethylammonium chloride] (PMETAC) was studied under moderate (10 kHz) magic-angle spinning (MAS). To elucidate the role of adsorbed water in spin diffusion and proton conductivity, PMETAC was degassed under vacuum. The CP MAS results were processed by applying the anisot...
Preprint
Full-text available
The low signal-to-noise ratio is a characteristic feature of NMR experiments in the Earth magnetic field. The main problem of such studies is the ineffectiveness of signal accumulation due to fluctuations of the Earth magnetic field because of magnetic interferences from laboratory equipment and other magnetic field sources. Taking into account the...
Article
Full-text available
Characterization of protein solutions is of great importance for biophysical research, pharmaceutical industry, and medicine. Particularly, the monitoring of the protein aggregation is crucial at all stages of biotechnological production and in the diagnosis of dangerous diseases. The present work is focused on a study of prospects and possibilitie...
Article
Full-text available
Previous works showed a significant increase in the rotational correlation time of the water bound to the hemoglobin S during the aggregation process under sickle cell disease. In this case, the contribution of “Curie-Spin” relaxation mechanism to proton relaxation may be expected. The Curie-Spin relaxation mechanism has been well described theoret...
Article
The 1H–13C cross-polarization magic angle spinning (CP MAS) kinetics was studied in poly(vinyl phosphonic acid) (pVPA), i.e. material with high degrees of freedom of proton motion along H-bonded chains. It has been shown that the CP kinetic data for the adjacent 1H–13C spin pairs can be described in the frame of the isotropic spin-diffusion approac...
Article
As the development of the work (J. Phys. Chem. B 2019, 123 (10), 2362–2372) we have investigated the translational mobility in the same set of dried imidazolium-based ionic liquids [bmim]A (A = BF4¯, NO3¯, TfO¯, I¯, Br¯, Cl¯) in a wide temperature range using NMR technique. It is shown that for the [bmim]⁺ cation the temperature dependencies of the...
Article
Full-text available
The nuclear magnetic resonance (NMR)-relaxation characteristics of protons in pure aqueous and buffer solutions of highly hydroxylated endofullerenols with paramagnetic gadolinium ions at ambient temperature have been studied. These systems were thoroughly characterized by SANS and examined by NMR at various resonance frequencies: f = 2 kHz–500 MHz...
Article
Full-text available
The detailed investigation of the local mobility in a set of dried imidazolium-based ionic liquids (1-butyl-3-methylimidazolium) in a wide temperature range and varying anions (BF<sub>4</sub>-, I-, Cl-, Br-, NO<sub>3</sub>-, TfO-) is presented. The measurements of temperature dependencies of the spin-lattice relaxation times of <sup>1</sup>H and <s...
Article
Complementary experiments with NMR ¹ H and ¹³ C spectroscopy, proton diffusometry, and relaxometry have been used to investigate the sodium N-lauroyl sarcosinate (SLS) micellar systems in aqueous solutions. The effects of concentration and temperature on molecular conformation, micellar structure, and molecular kinetic in the SLS solutions were stu...
Article
Full-text available
The possible difference in the properties upon doping the Sr2CaCu2O6 superconducting or blocking layers with Fe and Eu respectively was investigated in this work. The homogeneous Sr2−yEuyCaCu2O6+δ and Sr2CaCu2−xFexO6+δ (y = 0, 0.1, 0.5, x = 0, 0.05) compounds were produced by a high-pressure synthesis route. Judging by the magnetic susceptibility m...
Article
Full-text available
Unique combination of ionic conductivity and anisotropic physical properties in ionic liquid crystals leads to new dynamic properties exploited in modern technological applications. Structural and dynamics information at atomic level for molecules and ions in mesophases can be obtained by nuclear magnetic resonance (NMR) spectroscopy through the me...
Article
Full-text available
The high data point density measurements of ¹H→¹¹B cross-polarization (CP) kinetics upon magic-angle spinning (MAS) of [bmim][BF4] confined in mesoporous SBA-15 and MCM-41 were carried out. The complex shaped ¹¹B CP MAS signals were observed in both silica and decomposed into two Lorentz components. This points towards the possibility of bimodal di...
Article
Full-text available
The effect of concomitant magnetic fields emerging in conjunction with encoding gradients, which is important in the process of the magnetic resonance imaging in low fields, has been considered. The manifestations of concomitant magnetic fields in a concrete gradient system, namely in the system of two coaxial gradient coils, have been thoroughly a...
Article
We have simulated the melt of poly(carbosilane) dendrimers using atomistic models and have reproduced the effect predicted by the analytical theory; i.e., orientational autocorrelation functions of a segment from the same layer (numbered from periphery) are practically identical and do not depend on dendrimer size. The frequency dependences of the...
Article
It is shown on the basis of the data of three complementary methods (NMR-relaxation, Car-Parrinello molecular dynamics and quantum-chemical calculations) that the environment of the cation Ca2 + in aqueous solutions consists of two layers with different molecular mobility: the number of water molecules in the first hydration shell is n1 = 6, and fo...
Article
The series of unsubstituted Sr2CaCu2O6 and iron-substituted Sr2CaCu2−x Fex O6 () materials were produced by a high-pressure synthesis route and characterized using X-ray diffraction and SQUID magnetometry. The change of contained phase ratio was found at different substituent concentrations in the samples synthesized under the same conditions: unex...
Article
Full-text available
We have studied copolymer dendrimer structure: carbosilane dendrimers with terminal phenylbenzoate mesogenic groups attached by poly(ethylene) glycol (PEG) spacers. In this system PEG spacers are additional tuning to usual copolymer structure: dendrimer with terminal mesogenic groups. The dendrimer macromolecules were investigated in a dilute chlor...
Article
Dipolar recoupling is an essential part of current solid-state NMR methodology for probing atomic-resolution structure and dynamics in solids and soft matter. Recently described magic-echo amplitude- and phase-modulated cross-polarization heteronuclear recoupling strategy aims at efficient and robust recoupling in the entire range of coupling const...
Article
Full-text available
In this work Earth’s field nuclear magnetic resonance (EFNMR) technique for applications in security scanning devices has been presented. The EFNMR setup has been build based on Magritek low-frequency (0–1 MHz) KEA-2 NMR console. Excepting the NMR console, all components are home-made units, which are a first-order gradiometer RF probe, pre-polariz...
Article
Hydration phenomena play a very important role in various processes, in particular in biological systems. Water molecules in aqueous solutions of organic compounds can be distributed among the following substructures: (i) hydration shells of hydrophilic functional groups of molecules, (ii) water in the environment of nonpolar moieties and (iii) bul...
Chapter
Full-text available
The method of the detection and identification of different liquids on the basis of registration of NMR in the Earth magnetic field has been discussed. Some general aspects of the problem are considered to illustrate the near-term outlooks. In particular, the polarization of nuclei with an alternating magnetic field \(B^{{\ast}}(B^{{\ast}}\gg B_{0}...
Article
Conformational and reorientational dynamics of surfactant molecules confined within solid inorganic frameworks of nanostructured composites are studied by solid-state NMR. Since the organic part in the nanocomposites exhibits a great variation in the local molecular mobility, a significant challenge in these materials is to develop an experimental...
Article
By classical molecular dynamics, a series of solutions in the ternary water-lithium nitrate-calcium nitrate system is simulated. The radial distribution functions for different atom pairs are calculated, the coordination numbers are estimated, and the pattern of change of their first solvation shell composition with a change in the component ratio...
Article
Full-text available
1-Ethyl-3-methylimidazolium acetate was studied by NMR relaxation. The temperature dependences of the spin-lattice relaxation rates (1/T 1) for 1H and 13C were obtained. The curves with maxima were observed for the majority of the temperature dependences 1/T 1, which provided a reliable temperature dependence of the correlation times (τc). In the l...
Article
A series of solutions of the ternary LiNO3-Ca(NO3)(2)-H2O system is simulated under standard conditions by means of classical molecular dynamics (MD). Several variants of the potentials of interparticle interactions predicting different structures and compositions of the lithium cation hydration shell are used in the calculations. The coordination...
Article
Full-text available
The polarization of nuclei in the low static magnetic field B 0 with an alternating magnetic field B Ã ðB Ã) B 0 Þ at a very low frequency f m (but f m) 1/T 1 , where T 1 is the spin-lattice relaxation time) has been investigated. The question of the optimization of the energy consumption during the pre-polarization is also considered. The possibil...
Article
Full-text available
The temperature dependencies of (13)C NMR relaxation rates in [bmim]PF6 ionic liquid have been measured and the characteristic times (τc) for the cation reorientation have been recalculated. We found the origin of the incorrect τc temperature dependencies that were earlier reported for ring carbons in a number of imidazolium-based ILs. After a corr...
Chapter
Absorption or emission of energy by quantum systems as a result of their interaction with an electromagnetic field is the basis of all of the methods of quantum radio physics.
Chapter
Nuclear magnetic resonance in magnetically ordered materials was first observed by Gossard and Portis in the metallic cobalt on \(^{59}\)Co nuclei A. C. Gossard and A. M. Portis, Observation of Nuclear Resonance in a Ferromagnet. Phys. Rev. Lett. 3 (1959) 164–166. Since then numerous studies of different magnetically ordered materials were performe...
Chapter
The analysis of the nature of splitting of ion levels under the influence of the crystal field is based on the Wigner theorem and Eq. 10. 30.
Chapter
A very important aspect of the physics of magnetic resonance are so-called double resonances. The essence of the double resonance experiments consists in the influence on the selected spin resonance transition with continuous or pulsed alternating magnetic field and the registration of the response at another transition in the same or another spin...
Chapter
In isotropic liquids there are relatively fast rotational and translational movements of molecules.
Chapter
As we might expect, for the observation of NMR it is required permanent magnetic field \(\vec {B}_0\), in which the Zeeman splitting of energy levels of the spin system is realized, and a alternating radio frequency field \(\vec {B}_1\), stimulating transitions between the Zeeman sublevels.
Chapter
As it was already mentioned in Sect. 1. 11, interactions between electron and nuclear magnetic momenta are termed as hyperfine interactions (HFI)
Chapter
One of the applications of Quantum Radiophysics is quantum magnetometry, based on the phenomenon of magnetic resonance and optical orientation atomic and nuclear moments. Specialists in many fields of physics and engineering face the necessity of the magnetic measurements, but the long-known classical methods do not provide modern requirements to a...
Chapter
Liquid crystal or mesophase is a thermodynamic phase of matter which differs from isotropic liquids and single crystals.
Chapter
Already in the first papers on the ammonia maser, it was stated that if the self-excitation condition is not satisfied, the device can serve as an amplifier of microwave power with low intrinsic noises. This is due to the fact that the probability of spontaneous emission in the radio diapason is very low and noises of an amplifier are determined on...
Chapter
For the realization of the process of quantum amplification of electromagnetic waves it is necessary to create an anomalous difference the populations of energy levels: the population of the upper level must be greater than the lower one (see Sect. 17. 1). More over, it was shown in Sect. 3. 2, that it is impossible to create such stationary state...
Chapter
In Chap. 1 the concepts of the nuclear magnetic relaxation times (rates) were introduced on the basis of phenomenological considerations, as exemplified by the theory of Bloch.
Chapter
As it was already mentioned in Chap. 11, a main factor defining the structure of spectra of the electron paramagnetic resonance is the interaction of electrons with the nearest molecular environment and nuclei of atoms and the molecules forming a paramagnetic center.
Chapter
Nuclear quadrupole resonance (NQR) is one of the most sensible tools to study the local structure of materials, electronic density distributions near the nuclei under study, the nature of defects in solids, the mobility of molecules, or their parts, phase transitions and so on. It is very helpful to investigate physical properties of solids, molecu...
Chapter
Application of the NMR methods to solids provides much more information than for liquids or gases. The matter is that interactions, which determine NMR spectra of solids, in contrast to interactions in liquids, keep anisotropic properties. The main interactions are dipole–dipole interactions, quadrupole interactions, and interactions of nuclear mag...
Chapter
We have already met the situations when the crystal field model does not lead to correct results. This is the case of the strong crystal field when the interaction of surrounding ions or molecules with a paramagnetic center is comparable with electrostatic interactions of electrons in a ion.
Chapter
This part focuses the attention on the approach suitable for studying assemblies of weakly interacting paramagnetic centers. Here we will not consider magnetically ordered systems where ferromagnetic, ferrimagnetic or antiferromagnetic resonance phenomena can be observed, as well as systems with free electrons (metals and semiconductors).
Chapter
In nuclear quadrupole resonance, splitting of energy levels of a spin system occurs under the influence of the interaction between the nuclear quadrupole moment and intracrystalline electric field gradients. That allows us to observe NMR signals in zero or weak static magnetic field. The absence of electromagnets essentially decreases the necessary...
Chapter
In this and follow-up chapters we will describe the physical principles for the development of devices, in which an element that determines their properties is an ensemble of micro-particles (nuclei, atoms, molecules, and so on) in special state. In the classical radioelectronics, there are numerous devices that use the so-called narrow-band elemen...
Chapter
At present, there are both active and passive devices of the quantum radioelectronics, in which to increase the intensity of a spectral line in the radio diapason one uses an auxiliary radiation of optical range.
Chapter
Two-dimensional Fourier-transform spectroscopy of nuclear magnetic resonance is one of the capital and most extensive research concepts in the NMR spectroscopy that allows the investigation of complex systems of coupled nuclear spins. Usual one-dimensional spectra are failed to be decoded because of inevitable lineoverlap for large molecules.
Book
The book is devoted to the description of the fundamentals in the area of magnetic resonance. The book covers two domains: radiospectroscopy and quantum radioelectronics. Radiospectroscopy comprises nuclear magnetic resonance , electron paramagnetic resonance, nuclear quadrupolar resonance, and some other phenomena. The radiospectroscopic methods a...
Article
Full-text available
The interest to observe a NMR-signal from samples inside closed metallic containers may take place, for example, for special services with examination of hand luggage. It is difficult to register NMR-signal from such samples because the metal of enclosures forms a short-circuited turn, which significant reduces a Q-quality of receiving contour. Fur...
Conference Paper
According to H-1 NMR study in fcc hydrides of disordered Ti-V alloys hydrogen atoms are distributed over both octahedral and tetrahedral sites. The occupancy of octahedral sites increases with the vanadium concentration. In hydrides of ternary Ti-V-Cr alloys hydrogen atoms occupy tetrahedral sites only.
Article
This paper presents a theoretical and experimental study of nuclear magnetic resonance technique for sign-sensitive determination of the dipolar couplings of rare spins-1∕2 to spin-1 with a strong quadrupolar interaction. The technique is based on low-power transition-selective single-quantum decoupling of spin-1 in the presence of high-power decou...
Article
Efficiency of the proton detected (encoded) (1)H-(13)C-(14)N local field spectroscopy technique at low radiofrequency power is examined when applied to concentrated ionic lyotropic mesophases exhibiting heteronuclear and homonuclear dipolar couplings in kHz range. We demonstrate that highly resolved heteronuclear dipolar spectra can be obtained wit...
Article
Different ion-water clusters for the CH3COO− ion that simulate the structure of its hydrate shells in solution are considered on the basis of the quantum mechanical approach. The possible coordination of water molecules around the ion is studied and the calculation results are compared with the experimental data obtained by nuclear magnetic relaxat...
Article
It has been found that the Cl− and Br− anions change the microstructure of their hydration shells in the temperature range 30–35°C. The effect was observed for simple salt solutions and ternary systems with different organic compounds. Probably this effect can be responsible for the thermoregulation of warm-blooded animals. KeywordsNMR–NMR-relaxat...
Article
Titanium-vanadium-chromium alloys are promising materials for hydrogen storage. They can absorb up to 3.8 wt % of hydrogen with a variable (depending on the composition) temperature of hydrogen release in a convenient range. This paper reports on the results of investigations of the TiV0.80Cr1.20H5.29 hydride by continuous-wave (cw) and pulsed 1H n...
Article
The experimental frequency and temperature dependences of proton spin-lattice relaxation in metallic hydrides are often treated within the Bloembergen-Purcell-Pound model. However, even the consideration of activation energy (or correlation time) distribution does not provide a satisfactory agreement with experimental data. It was experimentally de...
Article
Full-text available
A method is presented for determining microstructural parameters (coordination numbers of ions, mobilities of solvent molecules) of diamagnetic aqueous solutions from NMR relaxation data; it is based on the analysis of the concentration and temperature dependence of the relaxation rates of various nuclei belonging to solvent molecules and ions. The...
Article
The paper presents the results of temperature dependence measurements for the rate of proton relaxation (1/T 1) in sea water with salinity 35‰ over the temperature range −22−+120°C at atmospheric pressure and in some salt solutions at two concentrations (0.5 and 1 mol/l). The possibility of approximating the temperature dependences of magnetic rela...
Article
Characteristic features of the structure of Ca2+ hydration shells were considered. The results of quantum chemical calculations were compared with experimental data obtained from the study of nuclear magnetic relaxation of deuterons in aqueous solutions of calcium salts. The influence of the basis set and computational procedure on the calculated 2...