Ашық рұқсат
Рұқсат берілді
Тек жазылушылар үшін
Том 89, № 10 (2025)
Physics of magnetic phenomena: fundamental and applied research using magnetic resonance methods
Quantum mechanics simulation of free induction decay for the magnetic centers on a spherical nanoparticle
Аннотация
By direct numerical solution of the Schrödinger equation for spins system we study free induction decay (FID) of diamagnetic nanospheres modified by deposition of atoms with non-zero magnetic moments. Simulations show that 10–14 interacting spins on the sphere is enough to describe FID and characteristic relaxation time reasonably well. We also compare the quantum spins description of FID with a phenomenological moment theory approach.
Bulletin of the Russian Academy of Sciences: Physics. 2025;89(10):1518–1525
1518–1525
Transmission of information using Mössbauer photons
Аннотация
We reported the first successful transmission of information using a random stream of Mössbauer photons. The gamma radiation was modulated using the quantum interference effect between the incident and forward-scattered resonant radiation. The proposed method will have significant advantages in terms of size and energy consumption compared to systems using X-ray tube radiation and will also allow information to be transmitted secretly.
Bulletin of the Russian Academy of Sciences: Physics. 2025;89(10):1526–1532
1526–1532
Influence of interface on magnetic resonance in films of the Fe-Bi system
Аннотация
We presented the results of experimental studies of two-layer films in the Fe-Bi system depending on the deposition order of the magnetic and non-magnetic layers. Using electron magnetic resonance method, it is shown that additional magnetic anisotropy of the easy-plane type takes place in Fe-Bi films. The observed changes are explained by the formation of a granular iron layer at the interface with bismuth, which has strong magnetic anisotropy.
Bulletin of the Russian Academy of Sciences: Physics. 2025;89(10):1533–1538
1533–1538
Features of the spin-wave description of the motion of a symmetric top in a weak magnetic field
Аннотация
A system considered is a ferromagnetic sample with a dipole-dipole interaction of particles in the absence of exchange effects, placed in a homogeneous weak magnetic field. The properties of a ferromagnet are described in the spin wave formalism. An analytical solution of systems of equations describing the dynamics of interacting magnetic moments in an external field of different orientations (longitudinal and transverse) relative to the axis of symmetry of the top is obtained, and a graphical visualization of the analytical solution of the system of equations of dynamics of magnetic moments is implemented.
Bulletin of the Russian Academy of Sciences: Physics. 2025;89(10):1539–1547
1539–1547
Influence of synthesis conditions on photoluminescent properties and paramagnetic centers of porous aluminum oxide formed in sulfuric acid
Аннотация
It is shown that it is possible to control the type and concentration of paramagnetic centers (F+ centers and molecular groups of Al-SO4) in anodic aluminum oxide and the intensity of dye photoluminescence (using rhodamine B as an example) in its pores by varying the temperature of the sulfuric acid-based electrolyte. The obtained samples are promising for the development of optical sensor platforms.
Bulletin of the Russian Academy of Sciences: Physics. 2025;89(10):1548-1554
1548-1554
Experimental confirmation of a new paradigm of spin exchange in dilute solutions of paramagnetic particles
Аннотация
The new paradigm of spin exchange and its manifestations in EPR spectroscopy contain provisions that are fundamentally different from the widespread initial paradigm of spin exchange. The new paradigm of spin exchange in dilute solutions is also of interest as an example of the formation of a coordinated spin coherence motion of an ensemble of spins in a dilute paramagnetic, and this consistency is achieved by random bimolecular collisions of paramagnetic particles, in fact, the «recoil effect» of spin coherence in random collisions of paramagnetic particles. The new paradigm of spin exchange and new protocols for analyzing experimental data will be more widely recognized and used as a tool, for example, to improve the accuracy of detecting the frequency of collisions of substrate molecules with receptors in molecular biology using EPR spectroscopy. The experimental evidence of the fundamental provisions of the new paradigm obtained in the last 2–3 years are discussed.
Bulletin of the Russian Academy of Sciences: Physics. 2025;89(10):1555–1565
1555–1565
Sorption and desorption of copper (II) cations on ethylenediamine phosphonic polyampholytes according to EPR data
Аннотация
The composition of polymer complexes of divalent copper in macroporous polyampholytes based on styrene-divinylbenzene copolymers containing phosphonic groups —CH2PO(OH)2 and ethylenediamine —CH2NH(CH2)2NH2 (en) groups was determined using the EPR method. It was shown that at low degrees of filling, polymer complexes [Cu(en)2(H2O)2]2+ containing 4 nitrogen atoms (complexes A) are formed. With further filling, complexes containing 2 nitrogen atoms [Cu(en)(H2O)4]2+ (complexes B), complexes with phosphonic groups Cu(R – HPO3)2(H2O)4 (complexes C) and aqua complexes Cu(H2O)62+ (complexes D) are also observed. Desorption of copper (II) ions by hydrochloric acid is accompanied by the rapid destruction of copper (II) complexes with ethylenediamine groups and the formation of copper (II) complexes with phosphonic groups and aqua complexes.
Bulletin of the Russian Academy of Sciences: Physics. 2025;89(10):1566–1572
1566–1572
Magnetic resonance signals arising during intensive division of Fagopyrum tataricum callus cells and their orientation behavior
Аннотация
The orientation behavior of electron magnetic resonance signals arising during the growth and division of buckwheat callus cells Fagopyrum tataricum (L.) Gaertn was studied. Three types of signals were detected two of them demonstrated angular dependencies. Angular dependencies were investigated for two types of signals. Magnetic anisotropy characteristics were obtained. They indicate a change in the geometry of the magnetic area in cell nuclei during their division.
Bulletin of the Russian Academy of Sciences: Physics. 2025;89(10):1573-1580
1573-1580
Electron paramagnetic resonance study of radicals in calcium gluconate in the W-band
Аннотация
Mechanically activated calcium gluconate was studied using the X- and W-range paramagnetic resonance method. The W-range spectrum is multicomponent and is described by contributions from two types of radicals with different g-factors: carbon radicals of δ-gluconolactone and the (Ca-OC6H11O6)·δ-GL radical. The parameters of these spectra obtained because of quantum-chemical calculations are in good agreement with the experimental ones.
Bulletin of the Russian Academy of Sciences: Physics. 2025;89(10):1581–1585
1581–1585
Mössbauer studies of molecular viscosity of frozen water layers in montmorillonite pores using 57Fe probe atoms
Аннотация
Within the framework of the Maxwell and Kelvin - Voigt models, using a set of exchange forms of the 57FE probe, the viscoelastic parameters of water layers in a natural mineral were established. A methodical approach and tested that allows confirming the concept of shear molecular viscosity. In is shown that the problem of its determination from Mössbauer studies can be solved using the Einstein, Debye and Frenkel models.
Bulletin of the Russian Academy of Sciences: Physics. 2025;89(10):1586–1594
1586–1594
A new functional series of mixed-ligand β-diketonate complexes of Fe(III), Ga(III) and Eu(III): evolution of magnetic states
Аннотация
A new series of heteroleptic halogen-substituted complexes with the general formula [XL2Bipy]Cl, where L is 1-(4-fluorophenyl)-3-(4-bromophenyl)-propane-1,3-dione, Bipy is 2,2-bipyridine, X is Fe3+, Ga3+ and Eu3+, was synthesized. Their structure and phase behavior were studied. Magnetic properties were investigated in a wide temperature range and their theoretical analysis was performed.
Bulletin of the Russian Academy of Sciences: Physics. 2025;89(10):1595-1604
1595-1604
Electrophysical and biological properties in vitro of lithium doped hydroxyapatite
Аннотация
The impact of varying lithium concentrations introduced into hydroxyapatite has been extensively documented, spanning a wide range of concentrations from 1 to 20 mol.%. It has been demonstrated that an increase in the content of Li+ ions is associated with enhanced growth of relative dielectric permittivity. Concurrently, the introduction of lithium does not elicit acute cytotoxicity and is conducive to the proliferation of MG-63 cells in vitro, as observed over a seven-day period.
Bulletin of the Russian Academy of Sciences: Physics. 2025;89(10):1605-1615
1605-1615
Anisotropic spin models for iridium oxides: justification in the cluster quantum chemical approach
Аннотация
For various crystal structures of magnetic iridium oxides, a quantum-chemical cluster method has been developed for quantitative justification of effective spin models, including the Heisenberg compass model on a square lattice and the Kitaev model on a hexagonal lattice, previously proposed on a phenomenological basis and currently being intensively discussed.
Bulletin of the Russian Academy of Sciences: Physics. 2025;89(10):1616-1622
1616-1622
Spin echo signal simulation of gaussian pulse protocol using phase cycling
Аннотация
The Carr–Purcell–Meiboom–Gill pulse sequence is widely used in magnetic resonance to measure the spin-spin relaxation time T2. The time T2 is a characteristic decay time of the refocused spin echo signals. Ideally, the refocusing pulses of this sequence should invert all the spins of the spectrum, i.e. have a rotation angle of 180°. This condition is met in NMR experiments, since the pulse amplitude in them is much larger than the spectrum width in magnetic field units. In the case of pulsed EPR, it is usually impossible to effectively invert all the spins of the spectrum by the refocusing pulse. In this situation, at the moments of echo observation, other signals appear that depend not only on the time T2, but also on the spin-lattice relaxation time T1. In this paper, numerical calculations of the echo signal amplitudes in the Carr–Purcell–Meiboom–Gill sequence with a Gaussian pulse shape are performed. Phase cycling of the sequence is proposed to isolate the refocused echo signals.
Bulletin of the Russian Academy of Sciences: Physics. 2025;89(10):1623-1630
1623-1630
Solution of Bloch equations in weak fields for study in express mode
Аннотация
It is shown that to expand the functionality of express mode research into the state of condensed matter using the phenomenon of nuclear magnetic resonance in weak fields, it is necessary to solve the Bloch equations considering the features of recording its signal during field modulation. New relationships were obtained for the absorption signals υ and dispersion u, as well as the z-component of the magnetization, which made it possible to obtain a new dependence in explicit form for determining the critical points of the absorption signal (for the other two quantities, the derivation of these dependencies is similar to that presented) on the field parameters, the autodyne circuit and the relaxation times T1 and T2 of the medium under study. Based on the analysis of the obtained relationships, a new expression using u and υ is proposed to describe the recorded NMR signal using the modulation technique. Comparing the results of the NMR signal calculation with the experiment are presented. The necessity of implementing automatic adjustment of the modulating field amplitude in the design of a mobile NMR relaxometer to increase the signal-to-noise ratio and reduce the influence of modulation effects on the research results is substantiated.
Bulletin of the Russian Academy of Sciences: Physics. 2025;89(10):1631–1643
1631–1643
Electron magnetic resonance signals in spinal cord tissues of rats
Аннотация
Three types of magnetic resonance signals with a g-value above 2.1 were found in rat spinal cord tissues: a wide signal independent on the sample orientation in magnetic field and two types of narrow signals — one-component and two-component with orientation dependence. The temperature behavior of these three types of signals has been studied. It is supposed that the wide signal may be due to ferritin crystal core; and the characteristics of the orientation-dependent signals correspond to the crystalline particles of magnetite.
Bulletin of the Russian Academy of Sciences: Physics. 2025;89(10):1644-1650
1644-1650
Diagnosis and restoration of patients’ vocal function using spectral analysis of voice and magnetic resonance imaging
Аннотация
The results of the diagnosis and rehabilitation of vocal disorders using computer spectral voice analysis method, dynamic magnetic resonance imaging, traditional methods of otorhinolaryngology and original rehabilitation techniques are presented. The use of standard and original voice tests, computer analysis of the voice spectrum can speed up diagnosis. The restoration of voice functions is carried out using original rehabilitation techniques under the control of a software and hardware complex.
Bulletin of the Russian Academy of Sciences: Physics. 2025;89(10):1651–1659
1651–1659
Condensed Matter Physics
The de Haas – van Alphen effect in two-dimensional metals at fixed electron density
Аннотация
The de Haas – van Alphen effect in two-dimensional metals is studied under various conditions and with an arbitrary forms of Landau levels. We consider the limit of fixed electron density and an intermediate situation with a finite reservoir of electronic states. An analytical formula for magnetization at a constant electron density and an arbitrary temperature is obtained.
Bulletin of the Russian Academy of Sciences: Physics. 2025;89(10):1660–1664
1660–1664
Study of the ultrafine-grained copper structure formed by dynamic recrystallization by analyzing the etched surface relief
Аннотация
The ultrafine-grained structure of technically pure copper formed by severe plastic deformation has been investigated by methods of structure state estimation including spatial distribution of grain boundary energies. The peculiarities of relaxation processes at the final stage of deformation have been established.
Bulletin of the Russian Academy of Sciences: Physics. 2025;89(10):1665–1670
1665–1670
Frequency dependence of dielectric permittivity of nickel-zinc ferrites
Аннотация
We described the methodology and results of measuring the relative dielectric permittivity εr of nickel-zinc ferrite M200VNP and M1000NN in the frequency range of 1–100 kHz. At frequencies below 50 kHz the investigated types of ferrites exhibit interfacial polarization, leading to abnormally high values of εr. At higher frequencies εr decreases to a constant value of approximately 12.
Bulletin of the Russian Academy of Sciences: Physics. 2025;89(10):1671–1677
1671–1677
Kinetics of heterogeneous boiling-up of moderately superheated n-pentane in a glass tube at pressures above atmospheric
Аннотация
The kinetics of spontaneous boiling-up of superheated n-pentane in a glass tube is investigated. It has been shown that the dependences of the mean lifetime of the superheated liquid on the depth of entry into the metastable region lie near one curve. The formation of vortex structures has been revealed in the initial stage of boiling-up of superheated n-pentane, thermostatically controlled in the middle of the tube.
Bulletin of the Russian Academy of Sciences: Physics. 2025;89(10):1678-1684
1678-1684