Kazan Physical Technical Institute

Kazan, Russia

Kazan Physical Technical Institute

Kazan, Russia
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Kazan S.,Gebze Institute of Technology | Sale A.G.,Gebze Institute of Technology | Gatiiatova Ju.I.,Kazan Physical Technical Institute | Valeev V.F.,Kazan Physical Technical Institute | And 3 more authors.
Solid State Communications | Year: 2010

The results of magnetic resonance and magnetization measurements of Fe-implanted strontium titanate (SrTiO3) are presented. Electron paramagnetic resonance (EPR) spectra including resonance lines due to the paramagnetic Fe3+-V o site with axially disturbed ligand field, and due to S-state Fe3+ ions (S = 5 / 2 and L = 0) substituted into the titanium site coordinated by six oxygen atoms in the Ti4+-centered unit cell, were observed. It has been revealed that the implantation of Fe ions into SrTiO3 produces a remarkable ferromagnetic behavior. The ferromagnetic resonance (FMR) and magnetization measurements revealed an out-of-plane uniaxial magnetic anisotropy in Fe-implanted SrTiO3. The observed phenomena are discussed on the basis of strong magnetic dipolar interaction between Fe nanoparticles due to the decreasing interparticle distance with increasing implantation fluence. © 2009 Elsevier Ltd. All rights reserved.

Krushelnitsky A.,Kazan Institute of Biochemistry and Biophysics | Zinkevich T.,Kazan Physical Technical Institute | Reichert D.,Martin Luther University of Halle Wittenberg | Chevelkov V.,Leibniz Institute for Molecular Pharmacology | Reif B.,Leibniz Institute for Molecular Pharmacology
Journal of the American Chemical Society | Year: 2010

For the first time, we have demonstrated the site-resolved measurement of reliable (i.e., free of interfering effects) 15N R1ρ relaxation rates from a solid protein to extract dynamic information on the microsecond time scale. 15N R1ρ NMR relaxation rates were measured as a function of the residue number in a 15N, 2H-enriched (with 10-20% back-exchanged protons at labile sites) microcrystalline SH3 domain of chicken α-spectrin. The experiments were performed at different temperatures and at different spin-lock frequencies, which were realized by on- and off-resonance spin-lock irradiation. The results obtained indicate that the interfering spin-spin contribution to the R 1ρ rate in a perdeuterated protein is negligible even at low spin-lock fields, in contrast to the case for normal protonated samples. Through correlation plots, the R1ρ rates were compared with previous data for the same protein characterizing different kinds of internal mobility. © 2010 American Chemical Society.

Kurbanov R.,Kazan Institute of Biochemistry and Biophysics | Zinkevich T.,Kazan Physical Technical Institute | Krushelnitsky A.,Martin Luther University of Halle Wittenberg
Journal of Chemical Physics | Year: 2011

The advantage of the solid state NMR for studying molecular dynamics is the capability to study slow motions without limitations: in the liquid state, if orienting media are not used, all anisotropic magnetic interactions are averaged out by fast overall Brownian tumbling of a molecule and thus investigation of slow internal conformational motions (e.g., of proteins) in solution can be conducted using only isotropic interactions. One of the main tools for obtaining amplitudes and correlation times of molecular motions in the μs time scale is measuring relaxation rate R1ρ. Yet, there have been a couple of unresolved problems in the quantitative analysis of the relaxation rates. First, when the resonance offset of the spin-lock pulse is used, the spin-lock field can be oriented under an arbitrary angle in respect to B0. Second, the spin-lock frequency can be comparable or even less than the magic angle spinning rate. Up to now, there have been no equations for R 1ρ that would be applicable for any values of the spin-lock frequency, magic angle spinning rate and resonance offset of the spin-lock pulse. In this work such equations were derived for two most important relaxation mechanisms: heteronuclear dipolar coupling and chemical shift anisotropy. The validity of the equations was checked by numerical simulation of the R1ρ experiment using SPINEVOLUTION program. In addition to that, the applicability of the well-known model-free approach to the solid state NMR relaxation data analysis was considered. For the wobbling in a cone at 30° and 90° cone angles and two-site jump models, it has been demonstrated that the auto-correlation functions G0(t), G 1(t), G2(t), corresponding to different spherical harmonics, for isotropic samples (powders, polycrystals, etc.) are practically the same regardless of the correlation time of motion. This means that the model-free approach which is widely used in liquids can be equally applied, at least assuming these two motional models, to the analysis of the solid state NMR relaxation data. © 2011 American Institute of Physics.

Lapaev D.V.,Kazan Physical Technical Institute | Nikiforov V.G.,Kazan Physical Technical Institute | Safiullin G.M.,Kazan Physical Technical Institute | Lobkov V.S.,Kazan Physical Technical Institute | And 3 more authors.
Optical Materials | Year: 2014

The study of the terbium(III) and gadolinium(III) β-diketonate complexes by photoluminescence spectroscopy reveals considerable changes of the photophysical properties of the complexes under the UV laser irradiation. The measurements show the enhancement of the luminescence intensities in the vitrified transparent film of the terbium(III) complex as well as the gadolinium(III) complex under the 337 nm laser irradiation at room temperature. The irradiated film of the terbium(III) complex restores the initial photophysical properties after heating close to the melting temperature (∼353 K) and cooling. We observe no change of the luminescent properties of the irradiated film for months. These features can be used for the design of new lanthanide-based photostable systems with laser control of the luminescence intensity. © 2014 Elsevier B.V. All rights reserved.

Ay F.,Gebze Institute of Technology | Aktas B.,Gebze Institute of Technology | Khaibullin R.I.,Kazan Physical Technical Institute | Nuzhdin V.I.,Kazan Physical Technical Institute | And 2 more authors.
Journal of Magnetism and Magnetic Materials | Year: 2014

The magnetic properties of Ni-implanted ITO thin films have been investigated by ferromagnetic resonance (FMR) technique and vibrating sample magnetometry (VSM) techniques. Commercially available ITO thin films on fused silica substrates have been implanted with different fluences of Ni+ ions with energy of 40 keV and ion current density of 8 μA/cm2 at room temperature. The samples with three doses of 0.5×1017, 1.0×1017 and 1.5×1017 ions/cm2 have been studied. Room temperature ferromagnetism has been observed in the nickel-implanted ITO samples with fluences of 1.0×1017 and 1.5×1017 ions/cm2. The magnetic properties of the samples have been explained by the formation of Ni-nanoparticles in the implanted surface layer of the ITO films. Although the formation of a diluted magnetic oxide phase cannot be ruled out entirely, the analysis of our FMR and VSM data reveals that the metallic Ni nanoparticles, formed during high-dose implantation process, have major contribution to the magnetic properties of the Ni-implanted ITO thin films. The sizes of the Ni-nanoparticles have been calculated from the blocking temperatures obtained by the VSM measurements. The filling factor of the Ni ferromagnetic phase in the granular magnetic layer has also been estimated by the effective magnetization approach applied to the FMR results. © 2014 Elsevier B.V. All rights reserved.

Mozzhukhin G.V.,Gebze Institute of Technology | Rameev B.Z.,Gebze Institute of Technology | Rameev B.Z.,Kazan Physical Technical Institute | Khusnutdinov R.R.,Kazan Federal University | And 2 more authors.
Applied Magnetic Resonance | Year: 2012

New method of multifrequency nuclear quadrupole resonance (NQR) for the explosive detection has been proposed. This technique consists of application of the series of composite excitation circles, each consisting of two or three successive pulses of different frequencies. In this work, we study in detail the multipulse sequence consisting of n excitation sets, each set consists of three pulses. The first pulse is applied with frequency ν-, the second pulse with frequency ν0, and the third pulse with frequency ν-, but with a shifted phase. The NQR signal is detected at the frequency ν+. The maximal amplitude of the detected signal is obtained by tuning the pulse parameters at frequencies ν- and ν0. We have shown that the phase of the NQR signal at the frequency ν+ second part of the composite pulse with the frequency ν0 the signals with different phases to suppress the spurious signals. The method could be used for increasing the NQR signal, avoiding the spurious signals and improving the reliability of NQR detection. Possible applications of the method for the explosive detection are also discussed. © 2012 Springer-Verlag.

Vlasova D.D.,Kazan Physical Technical Institute | Kalachev A.A.,Kazan Federal University
Bulletin of the Russian Academy of Sciences: Physics | Year: 2012

The possibility of observing collective spontaneous emission upon a cooperative transition in an ensemble of interacting optical center pairs embedded in a metamaterial is investigated. It is shown that when the effective refractive index tends to zero, the relaxation rate of excited atomic states substantially decreases, allowing us to observe collective effects on weaker cooperative transitions. © Allerton Press, Inc., 2012.

Guler S.,Gebze Institute of Technology | Rameev B.,Gebze Institute of Technology | Rameev B.,Kazan Physical Technical Institute | Khaibullin R.I.,Kazan Physical Technical Institute | And 2 more authors.
Journal of Magnetism and Magnetic Materials | Year: 2010

Single crystals of Mn-implanted TiO2 rutile have been investigated by electron paramagnetic resonance (EPR) technique at room temperature. We have observed an EPR signal on Mn4+ ions (S=frac(3, 2)) in the manganese-implanted single crystal TiO2 plates. Besides, weaker EPR signals due to Fe3+(S=frac(5, 2), L=0) and Cr3+(S=frac(3, 2)) ions have also been observed. Characteristic six-line splitting of the manganese EPR lines due to hyper-fine interaction with 55Mn nuclei (spin I=frac(5, 2)) has also been observed. Analysis of the EPR spectra shows that the manganese, iron and chromium ions substitute for Ti4+ ions in the TiO2 rutile host. Two structurally equivalent groups of the centers have been observed in the EPR spectra in correspondence with two octahedral positions of the Ti ions in the rutile structure. Spin Hamiltonian parameters for the crystal field of orthorhombic symmetry on the Mn4+, Fe3+ and Cr3+ centers have been obtained as result of computer modelling. © 2009 Elsevier B.V. All rights reserved.

Denisov D.G.,Kazan Federal University | Kashapov N.F.,Kazan Federal University | Kashapov R.N.,Kazan Physical Technical Institute
IOP Conference Series: Materials Science and Engineering | Year: 2015

In this paper, we have been tasked to investigate the transitional regime, to identify the main physical phenomena and give them a qualitative explanation. As a result of experimental researches, have been proposed and discussed possible mechanisms for generating shock waves in the transition region. © Published under licence by IOP Publishing Ltd.

Kashapov L.N.,Kazan Federal University | Kashapov N.F.,Kazan Federal University | Kashapov R.N.,Kazan Physical Technical Institute
IOP Conference Series: Materials Science and Engineering | Year: 2015

The article is devoted to the topic of anodic microdischarges in plasma-electrolyte processing. The aim of this work is to research the conditions of anodic micro-discharges during the plasma-electrolytic treatment and the influence they have on the surface of metals. As a result of experimental researches, was made a mechanism of influence anodic microdischarges on the surface of the electrode, burning of anodic microdischarges occur in the voltage range of 40-100 W. © Published under licence by IOP Publishing Ltd.

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