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1

Quantum magnetostriction effect resulting from the asymmetric structure of matter measured with EPR spectrometer

Sikoń Marek, Bidzinska Ewa

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2023

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Vol. 71, nr 1

art. no. e144575

EN

This paper explains the rotation and displacement as well as the couple and force stress in material with unpaired electrons/nucleons subjected to a magnetic field. This phenomenon is described in terms of quantum mechanics for nanoparticle and quantum statistical mechanics for loose nanomaterial. Quantitative calculations are carried out based on experimental data collected under the magnetic field of an EPR spectrometer from a set of nanocrystallites of hydrated copper sulfate.

2

The impact of propanol, n-butanol and pentanol on aqueous dispersions of sonicated liposomes. EPR study

Bartnikowska Agnieszka, Pytel Barbara, Man Dariusz

Ecological Chemistry and Engineering. S

|

2022

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Vol. 29, nr 4

565--579

EN

This paper presents the effect of selected alcohols on the fluidity of liposome membranes obtained in sonication of DPPC lecithin. Using the EPR technique, the duality of propanol, n-butanol and pentanol on the behaviour of the aqueous dispersion of liposomes was demonstrated. It was shown that after exceeding a certain concentration, these alcohols initiate dispersion foaming, leading to phase separation: liposome dispersion - lipid foam. The influence of the shape of the molecule and the length of hydrocarbon chains on the effectiveness of destabilisation of the structure of lipid membranes was indicated.

3

Study on irradiated D-mannose isolated from cranberry

Guzik Grzegorz P., Stachowicz Wacław, Michalik Jacek

Nukleonika

|

2019

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Vol. 64, No. 4

139--143

EN

The stable EPR signal produced by ionizing radiation in crystalline D-mannose (C6H12O6) and separated from cranberries (Vaccinium oxycoccus) was studied. The isothermal heating of irradiated sample at 95°C for 10 minutes (melting point of D-mannose is 132°C) resulted in the modifi cation and simplifi cation of the EPR signal involved. The isotropic quartet has been recognized in the EPR signal of heat-treated sample. Molecular structure of the isotropic quartet identifi ed in the complex EPR signal of D-mannose crystallite is proposed.

4

Electron paramagnetic resonance study of impurities and point defects in oxide crystals

Stefaniuk I.

Opto-Electronics Review

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2018

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Vol. 26, No. 2

81--91

EN

In this topic review the results of the X-band electron paramagnetic resonance (EPR) measurements of Mn, Co, Cr, Fe ions in YAlO₃ (YAP) crystals and Fe ions in LiNbO₃ (LNO) crystals and of chromium doped Bi₁₂GeO₂₀ (BGO) and Ca₄GdO(BO₃)₃ single crystals, are presented. It is well known that the oxide crystals (for example:YAP, LNO, BGO) are one of the most widely used host materials for different optoelectronic applications. The nature of point defect of impurities and produced in the oxide crystal after irradiation by bismuth ions and after irradiation by the ²³⁵U ions with energy 9.47 MeV/u and ﬂuency 5 × 10¹¹ cm⁻¹ is discussed. The latter is important for applications of these oxide crystal as laser materials.

5

Structural and optical properties of VO2+ doped methacrylic acid ethylacrylate (MAA:EA) copolymer films

Kumar Y. M., Bhyagyasree K., Gopal N. O., Ramu C.

Materials Science Poland

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2018

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Vol. 36, No. 1

34--41

EN

Pure and VO2+ doped methacrylic acid ethylacrylate (MAA:EA) copolymer films were prepared by using a solution casting method. Various techniques including X-ray diffraction, Fourier transform infrared spectroscopy, ultraviolet-visible spectroscopy, scanning electron microscopy and electron paramagnetic resonance were employed for characterization of the samples. XRD patterns showed some degree of crystallinity of the doped polymer films due to interaction of the MAA:EA copolymer with VO2+. FT-IR spectral studies of pure and VO2+ doped MAA:EA copolymer films displayed significant structural changes within the doped copolymer film indicating the complexation. The optical absorbance of the pure and VO2+ doped films were measured in the 200 nm to 800 nm wavelength range. The values of the absorption edge and indirect band gaps were calculated. The optical band gap decreased with the increase of mol% of VO2+. From the EPR spectra, the spin- Hamiltonian parameters (g and A) were evaluated. The values of the spin-Hamiltonian parameters confirmed that the vanadyl ions were present in MAA:EA copolymer films as VO2+ molecular ions in an octahedral site with a tetragonal compression (C4v). The morphology of the copolymer samples was examined by scanning electron microscopy. The enhanced crystalline nature of the doped copolymer was identified from SEM analysis.

6

The Microwave Sources for EPR Spectroscopy

Hruszowiec M., Nowak K., Szlachetko B., Grzelczak M., Czarczyński W., Pliński E. F., Więckowski T.

Journal of Telecommunications and Information Technology

|

2017

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nr 2

18--25

EN

Rapid development of many scientific and technical disciplines, especially in material science and material engineering increases a demand for quick, accurate and cheap techniques of materials investigations. The EPR spectroscopy meets these requirements and it is used in many fields of science including biology, chemistry and physics. For proper work, the EPR spectrometer needs a microwave source, which are reviewed in this paper. Vacuum tubes as well as semiconductor generators are presented such as magnetron, klystron, traveling wave tube, backward wave oscillator, orotron, gyrotron, Gunn and IMPATT diodes. In this paper main advantages of gyrotron usage, such as stability and an increased spectral resolution in application to EPR spectroscopy is discussed. The most promising and reliable microwave source is suggested.

7

Study of magnetic defects in NB2VSBO10 and NB6VSB3O25 compounds

Typek J., Bobrowska M.

Problemy Nauk Stosowanych

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2016

|

T. 5

93--98

EN

Introduction and aim: Two new compounds from the Nb-V-Sb-O system will be scrutinized as possible catalysts, because many compounds from this system has showed promising catalytic properties. Since there is often a direct link between the number of defects and catalytic activity of a compound, these two materials will be investigated by magnetic methods to detect existing defects and to determine their structure and properties. Material and methods:NB2VSBO10and NB6VSB3O25 are relatively new compounds synthesized in Department of Inorganic and Analytical Chemistry, West Pomeranian University of Technology, Szczecin. Two magnetic methods have been used - dc magnetisation and electron paramagnetic resonance (EPR) spectroscopy. Results: Although the nominal valences of metal ions in both compounds suggested non-magnetic properties, very complex magnetic response was registered in both magnetisation and EPR measurements. Non-homogeneous distribution of magnetic ions makes possible formation of different types of spin clusters and strongly interacting magnetic subsystems. Conclusion: NB6VSB3O25 seems to be more promising catalyst than NB2VSBO10 as there are more magnetic defects in this compound.

PL

Wstęp i cel: Dwa nowe związki z układu Nb-V-Sb-O będą rozważane jako potencjalne katalizatory, gdyż wiele związków z tego układu wykazuje obiecujące właściwości katalityczne. Ponieważ często pomiędzy ilością defektów a aktywnością katalityczną istnieje zależność proporcjonalna, dwa te związki będą badane metodami magnetycznymi aby wykryć istniejące w nich defekty oraz określić ich strukturę i właściwości. Materiały i metody: NB2VSBO10 and Nb6VSb3O25zostały zsyntezowane stosunkowo niedawno w Katedrze Chemii Nieorganicznej i Analitycznej Zachodniopomorskiego Uniwersytetu Technologicznego w Szczecinie. Zastosowano dwie metody badania właściwości magnetycznych - stałoprądową magnetyzację i spektroskopii elektronowego rezonansu paramagnetycznego (EPR). Wyniki: Chociaż nominalna wartościowość jonów metali w obu związkach sugeruje brak magnetycznych właściwości, zarejestrowano bardzo złożoną odpowiedź magnetyczną w pomiarach magnetyzacji i EPR. Niejednorodny rozkład jonów magnetycznych powoduje tworzenie się różnego rodzaju klasterów spinowych i silnie oddziaływujących podukładów magnetycznych. Wnioski: NB6VSB3O25wydaje się być bardziej obiecującym katalizatorem niż NB2VSBO10, ponieważ w tym związku jest dużo więcej defektów magnetycznych.

8

Temperature study of magnetic resonance spectra of co-modified (Co,N)-TiO2 nanocomposites

Guskos N., Typek J., Zolnierkiewicz G., Guskos A., Berczynski P., Dolat D., Mozia S., Aidinis K., Kruk K., Morawski A. W.

Materials Science Poland

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2016

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Vol. 34, No. 2

242--250

EN

The (nCo,N)-TiO2 (n = 1, 5 and 10 wt.% of Co) nanocomposites were investigated by magnetic resonance spectroscopy in 4 K to 290 K range. Analyses of ferromagnetic/electron paramagnetic resonance (FMR/EPR) spectra in terms of four Callen lineshape components revealed the existence of two types of magnetic centers, one derived from metallic cobalt nanoparticles in superparamagnetic (SPM) phase and the other from cobalt clusters in the TiO2 lattice. Additionally, at low temperature the EPR spectrum arising from Ti3+ ions was also registered. Both relaxations of the Landau-Lifshitz type and the Bloch-Bloembergen type played an important role at high temperature in determining the linewidths and the latter relaxation was prevailing at low temperature. Analysis of the integrated intensity showed that the SPM signal is due to small size FM cobalt nanoparticles while the paramagnetic signal from Co clusters originates from those nanoparticles in which the concentration of magnetic polarons is below the percolation threshold.

9

High temperature EPR study of the M3Fe4V6O24 (M = Cu, Zn, Mg and Mn)

Guskos N., Zolnierkiewicz G., Typek J., Pilarska M., Aidinis C., Blonska-Tabero A.

Materials Science Poland

|

2016

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Vol. 34, No. 3

517--522

EN

Electron paramagnetic resonance (EPR) spectra of M3Fe4 V6 O24 (M = Cu, Zn, Mg and Mn) compounds in high temperature range (293 K to 493 K) have been investigated. The role of magnetic (Cu, Mn) and non-magnetic (Zn, Mg) ions in M3Fe4 V6 O24 structure in formation of magnetic resonance spectra was studied. Temperature dependence of EPR parameters: resonance field, linewidth and integrated intensity were examined. Similarities and differences in temperature behavior of these parameters has been discussed in terms of different relaxation mechanisms and magnetic interactions in the spin systems. An important role of additional magnetic ions (M = Mn or Cu) in the M3Fe4 V6 O24 structure has been identified and its consequences considered.

10

Metody badania charakterystyki katalizatorów. Część I. Struktura i uporządkowanie katalizatora

Gryboś J., Kaczmarczyk J., Mazur T., Sobańska K.

Nafta-Gaz

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2015

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R. 71, nr 1

47--55

PL

Praca obejmuje zwarty przegląd podstaw teoretycznych i zastosowań metod badawczych o wysokim potencjale użycia w katalizie heterogenicznej. Autorzy przedstawili cztery techniki: rentgenowską dyfraktometrię proszkową (XRD), obliczenia DFT, transmisyjną mikroskopię elektronową (TEM) oraz elektronowy rezonans paramagnetyczny (EPR). Dyfraktometria rentgenowska pozwala, poprzez zbadanie uporządkowania dalekozasięgowego w objętości próbki, określić fazy krystaliczne obecne w próbce, wielkość domen dyfrakcyjnych oraz bardziej dokładnie przedstawić strukturę komórki elementarnej materiału katalitycznego. Metody obliczeniowe, bazujące na określonych założeniach teoretycznych, umożliwiają uzyskanie informacji niezbędnych do wyjaśnienia mechanizmów zachodzących reakcji, pozwalając w efekcie na zwiększenie dokładności przewidywanych wyników. Wymagają one jednak wcześniejszej weryfikacji zgodności modelu obliczeniowego z doświadczeniem. Transmisyjna mikroskopia elektronowa stanowi idealne narzędzie do analizy zarówno składu (techniki spektroskopowe: EDX, EELS), jak i struktury (w tym defektów) katalizatorów (techniki mikroskopowe: HR TEM, HR i HAADF STEM). Spektroskopia elektronowego rezonansu paramagnetycznego daje wgląd w najbliższe otoczenie koordynacyjne jonów paramagnetycznych oraz mechanizm reakcji katalitycznych. Komplementarne wykorzystanie wyników otrzymanych wymienionymi metodami pozwala uzyskać kompleksową wiedzę o uporządkowaniu blisko- i dalekozasięgowym katalizatora.

EN

The article covers a compact overview of the theoretical basics and usage of research methods with high potential for application in heterogeneous catalysis. The authors presented four techniques: X-ray powder diffraction (XRD), DFT calculations, transmission electron microscopy (TEM) and electron paramagnetic resonance (EPR). X-ray diffraction allows by means of examination of the long-range arrangement in sample volume, to determine crystalline phases, size of the crystal domains and to obtain the structure of the primitive cell of the catalytic material. Computational methods give the information necessary to fully explain the mechanisms of reactions, with higher resolution than by any experimental method. They require though, previous verification of computed model systems. Transmission electron microscopy is an ideal tool for the analysis of both the composition (spectroscopic techniques: EDX, EELS) and structure (including defects) of catalysts (microscopic techniques: HR TEM, HR and HAADF STEM). Electron paramagnetic spectroscopy gives insight into the nearest coordination surroundings of the paramagnetic ions and into the mechanisms of catalytic reactions. Complementary usage of the outcomes from each method mentioned above gives the comprehensive knowledge of both short- and long-range order in catalytic material.

11

Nowoczesne techniki spektroelektrochemiczne jako narzędzie dla badania procesów przeniesienia ładunku w polimerach skoniugowanych

Jarosz T., Krukiewicz K., Łapkowski M., Domagała W.

Chemik

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2015

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Vol. 69, nr 8

485--490

PL

Techniki elektrochemiczne, pozwalające monitorować procesy przeniesienia ładunku, są szeroko wykorzystywane do badania związków organicznych z grupy polimerów skoniugowanych. Materiały te znajdują zastosowanie w optoelektronice i są podstawą opracowania takich urządzeń elektroniki organicznej jak nowoczesne panele fotowoltaiczne, diody elektroluminescencyjne, tranzystory polowe, okna elektrochromowe i sensory chemiczne. Właściwości tych materiałów oraz ich zmiany podczas przebiegu procesów przeniesienia ładunku są jednym z głównych tematów badań prowadzonych z wykorzystaniem technik spektroelektrochemicznych w Katedrze Fizykochemii i Technologii Polimerów Politechniki Śląskiej. Sztandarową techniką należącą do tej grupy jest spektroelektrochemia EPR-UV-Vis-NIR, pozwalająca jednocześnie śledzić zmiany właściwości optycznych układów skoniugowanych i powstawanie oraz zanik nośników ładunku. Powiązanie ze sobą tych informacji pozwala na przypisanie, obserwowanym w warstwie polimerowej, rodzajom nośników ładunku przejść elektronowych i kompleksowa dyskusja zachodzących procesów domieszkowania/ oddomieszkowania.

EN

Electrochemical analysis techniques, allowing charge transfer processes to be followed, are frequently utilised in the study of organic compounds belonging to the group of conjugated polymers. These materials are widely used in optoelectronics and are the basis for the development of organic electronics devices, such as modern photovoltaic panels, light-emitting diodes, field effect transistors, electrochromic windows and chemical sensors. The physicochemical properties of these materials and their changes in the course of charge transfer processes are one of the main topics of research, conducted with the use of spectroelectrochemical techniques, in the Department of Physical Chemistry and Technology of Polymers at the Silesian University of Technology. The leading technique belonging to this group is EPRUV- Vis-NIR spectroelectrochemistry, allowing the changes in optical properties of conjugated systems to be followed simultaneously with the generation and decay of charge carriers. Joint consideration of this information allows electronic transitions, observed in the polymer layer, to be assigned to types of charge carriers types and the processes of doping / dedoping to be comprehensively discussed.

12

Study of magnetic properties of two samples from FeVO4-Co3V2O8 system

Guskos N., Zolnierkiewicz G., Typek J., Szymczak R., Guskos A., Berczynski P., Blonska-Tabero A.

Materials Science Poland

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2013

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Vol. 31, No. 4

601--610

EN

Two samples containing phases formed in the FeVO4–Co3V2O8 system were prepared by a conventional sintering method. The sample designated as H5 was one-phase with the howardevansite-type structure, while the sample designated as HL7 contained a mixture of H-type and lyonsite-type structures. The temperature dependence of the electron paramagnetic resonance (EPR) spectra and static magnetic susceptibility c was investigated in the temperature range from liquid helium to room temperature. Both the EPR spectra and the dc magnetic susceptibility showed anomalous behavior indicating that the magnetic competition process may be responsible. A comparison of the obtained results with previous studies on related compounds with the same structure, i.e. M3Fe4V6O24 (M = Mg(II), Zn(II), and Cu(II)) revealed that the observed anomaly shifted to lower temperatures on replacing the non-magnetic ions by magnetic Co(II) ions. The temperature dependence of the inverse susceptibility c􀀀1 indicates the existence of antiferromagnetic interactions between Fe(III) and Co(II) spins in sample H5. The obtained values of the Curie-Weiss temperatures are lower than for the Mn3Fe4V6O24 compound and comparable to compounds from M3Fe4V6O24 systems with M diamagnetic cations. The introduction of cobalt cations intensifies the magnetic frustration what is reflected in the temperature dependence of the magnetic susceptibility at low temperatures.

13

Elektronowy rezonans paramagnetyczny nanokompozytów (CoFeZr)x(Al2O3)(100-x) wytwarzanych rozpylaniem jonowym

Zhukowski P., Kołtunowicz T. N., Sidorenko J., Fedotova J.

Przegląd Elektrotechniczny

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2012

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R. 88, nr 7a

324-326

PL

W pracy przedstawiono wyniki badań metodą elektronowego rezonansu paramagnetycznego (EPR) właściwości magnetycznych nanokompozytów (CoFeZr)x(Al2O3)(100-x) wytworzonych rozpylaniem jonowym w atmosferze argonu (próbki beztlenowe) oraz argonu i tlenu (próbki tlenowe). Ustalono, że w badanych materiałach występuje pojedyncza linia EPR, parametry której Hmin, Hmax, Hg oraz czynnik g wykazują silną zależność kątową. Jest ona związana ze zmianą czynnika rozmagnesowania z kątem ustawienia próbki w stosunku do wektora natężenia pola magnetycznego. Wektor namagnesowania w próbkach beztlenowych jest większy, niż w próbkach tlenowych co jest związane z udziałem części atomów metali w związkach z tlenem. Wygrzewanie termiczne do Ta = 450°C powoduje wzrost wektora namagnesowania i czynnika g.

EN

The paper presents results of studies with the method of electron paramagnetic resonance (EPR) on properties of magnetic nanocomposites (CoFeZr)x(Al2O3)(100-x) produced by ion sputtering in an argon atmosphere (anaerobic samples) or argon and oxygen atmosphere (aerobic samples). It was found that there is a single EPR line in the material studied which parameters like Hmin, Hmax, Hg and a factor g show a strong angular dependence. It is connected with the change of the demagnetization factor according to the sample set angle relative to the vector of magnetic field strength. Magnetization vector in the anaerobic samples is larger than in aerobic samples that is connected with the participation of the certain metal atoms in compounds with oxygen. Thermal annealing up to the value of Ta = 450°C causes increase of the magnetization vector and the factor g.

14

Wielofunkcyjny system komputerowy do współpracy ze spektrometrem EPR

Stefaniuk I., Cieniek B.

Elektronika : konstrukcje, technologie, zastosowania

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2012

|

Vol. 53, nr 2

96-99

PL

W pracy opisano wykonanie nowatorskiego sprzęgnięcia komputera ze spektrometrem EPR. Polega ono na bezkonfliktowej pracy systemu z zapisem analogowym na rejestratorze XY, lub z zapisem cyfrowym na komputerze. Możliwy jest także równoczesny zapis na obu systemach. Do zaprogramowania i cyfrowej obróbki sygnału użyto środowisko LabVIEW, które standardowo zawiera wiele procedur poprawiających stosunek sygnału do szumów. Ta modernizacja pozwala na uzyskiwanie znacznie lepszych wyników niż tradycyjne metody, w krótszym czasie, co jest ważne w pomiarach szczególnie w funkcji temperatury. Pomiar temperatury dokonywany jest za pomocą dwóch różnych układów termopar. Wszystkie mierzone wartości są rejestrowane w czasie rzeczywistym z równoczesną wizualizacją widma na ekranie monitorze. System umożliwia cyfrową obróbkę sygnałów już w trakcie trwania pomiarów. Na zmodernizowanym spektrometrze wykonano dużo wartościowych pomiarów, z których część została przedstawiona na międzynarodowych konferencjach i opublikowana.

EN

This paper describes an innovative implementation of a computer connection with an EPR spectrometer. It's a conflict-free system for recording to an analog XY recorder, or with digital recording on a computer. There is also a possibility to simultaneously record on both systems. Lab VIEW environment was used in the area of programming and digital signal processing, which typically includes many procedures to improve the signal-to-noise ratio. This upgrade allows obtaining much better results than traditional methods in less time, which is especially important in measurements as a function of temperature. Measurements of temperature were performed using two different thermocouple. AU measured values are recorded in real time with simultaneous visualization of the spectrum on the screen. The system enables digital signal processing during the measurements. Using a modernised spectrometer, a lot of valuable measurements were made, some of which were been presented at international conferences and already published.

15

The effect of paramagnetic doping on the dielectric response of K1.85Na0.15Ti4O9 layered ceramics

Vikram S. V., Maurya D., Chandel V. S.

Materials Science Poland

|

2009

|

Vol. 27, No. 1

191--199

EN

Ceramic samples of layered polycrystalline (K1.85Na0.15)Ti4O9:xCu (0 ? x ? 0.8) have been prepared using high temperature solid state reaction. Room temperature X-ray diffratograms confirm the phase evolution. Room temperature electron paramagnetic resonance (EPR) data show that Cu2+occupies Ti4+ lattice sites giving rise to electric dipoles which increases electric permittivity. The absorption peak in EPR spectra gets broadened due to increased exchange interaction in heavily doped derivatives. Dielectric data reveal that occupancy of Cu2+ on Ti4+ leads to a decrease in dielectric losses and an increase in the electric permittivity as well.

16

Influence of oxygen O2 on microwave saturation of EPR lines of plants carbonized at 650°c and potential application in medicine

Pilawa B., Bartłomiejczyk S., Krzesińska M., Pusz S., Zachariasz J., Wałach W.

Engineering of Biomaterials

|

2008

|

Vol. 11, no. 73

9-11

EN

Electron paramagnetic resonance spectroscopy (EPR) was used to examination of spin-lattice relaxation in vascular plants carbonized at 650°C. Application of EPR method of continuous microwave signal saturation in medicine was proposed. The first derivative EPR spectra of pyrolysed bamboo and yucca were measured for samples in air and in vacuum. Influence of microwave power in the range 0.7-100 mW on amplitudes of EPR lines were evaluated. It was stated that amplitudes of the studied carbon materials increase with increasing of microwave power in the studied range. Saturation of EPR lines was not observed, so fast spin-lattice relaxation processes exist in the analyzed materials. Changes of EPR amplitudes for samples in air were slower than for evacuated samples. This effect may be used for determination of oxygen contents in the biological cells cultures and for analysis of optimal parameters of photodynamic therapy of cancer.

17

Comparatwe EPR analysis of oxygen interactions with plants carbonized at different temperatures

Bartłomiejczyk S., Pilawa B., Krzesińska M., Pusz S., Zachariasz J., Wałach W.

Engineering of Biomaterials

|

2008

|

Vol. 11, no. 73

3-5

EN

Carbon materials, bamboo (Bambusa vulagris) and yucca (Yucca flaccida) pyrolysed at 550°C, 750°C and 950°C, were tested as oximetric probes by electron paramagnetic resonance spectroscopy at X-band (9.3 GHz). The following parameters of the spectra: amplitude, linewidth and g-factor, were determined. Influence of oxygen molecules 02 on EPR spectra of the individual carbon materials was compared. Strong EPR spectra were recorded for samples carbonized at 550°C and weak signals were obtained for plants carbonized at higher temperatures: 750°C and 950°C. It was stated that amplitudes of EPR lines of all the carbonized plants decrease in the air environment compared to amplitudes of spectra measured in vacuum. This effect increases with degree of vacuum. Changes in the EPR spectra of samples studied in the air environment may be applied in medicine to determination of oxygen content in different cells. Because of strong resonance signals as oximetric probes we proposed bamboo and yucca carbonized at 550°C, and we rejected plants carbonized at 750°C and 950°C with Iow EPR signals.

18

Electric-dipole spin resonance in wurtzite ZnO

Michaluk E., Wilamowski Z., Błoniarz J., Mycielski A.

Optica Applicata

|

2006

|

Vol. 36, nr 2-3

291-296

EN

The electron spin resonance (ESR) measurements of the electric-dipole spin resonance (EDSR) of donor-bound electrons in ZnO wurtzite crystals are reported. This phenomenon was measured in longitudinal Voigt geometry (E1 | | B0 c) at low magnetic field and at low microwave frequency. The ESR transitions observed consist of two comparable signals: magnetic dipole spin resonance (MDSR) and electric dipole spin resonance (EDSR).

19

Magnetic resonance study of M3Fe4V6O24 (M = Mg, Zn, Mn, Cu, Co) compounds

Guskos N., Typek J., Zolnierkiewicz G., Blonska-Tabero A., Kurzawa M., Bosacka M.

Materials Science Poland

|

2005

|

Vol. 23, No. 4

923--928

EN

Multicomponent vanadates, M3Fe4V6O24 (M = Mg(II), Mn(II), Zn(II), Co(II) and Cu(II)), have been synthesized by the solid-state reaction method using a stoichiometric mixture of MO, Fe2O3, and V2O5 oxides. They crystallize in the triclinic space ace group P1 and have a complicated structure with two metal ion subsystems. Electron paramagnetic resonance (EPR) measurements have been performed at room temperature and an intense, almost symmetric EPR lines were recorded for all investigated samples except Co3Fe4V6O24. The integral intensity and linewidth of this line essentially depends on the kind of M(II) metal ion in the crystalline matrix. The EPR line intensity for the sample Co3Fe4V6O24 is over one order of magnitude smaller than for all other investigated compounds, and the position of its resonance line is shifted towards lower magnetic fields. The difference in linewidths and intensities are due to the various magnetic interactions between magnetic ions in the lattice, especially for systems containing two different magnetic ions.

20

Dependence of luminescence characteristics of irradiated quartz with the thermal treatment and consequences for TL dating

Roque C., Guibert P., Duttine M., Vartanian E., Chapoulie R., Bechtel F.

Geochronometria

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2004

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Vol. 23

1-8

EN

The dependence of luminescence properties of archaeological quartz pebbles with their thermal history is investigated and consequences for TL-dating are examined; the archaeological samples studied were collected from Solutrean layers at Laugerie Haute West rock shelter (Dordogne, France). This study is supported by a simulation experiment carried out on a natural quartz, using a combined approach by Cathodoluminescence (CL), Thermoluminescence (TL) and Electron Paramagnetic Resonance (EPR) techniques. The quartz grains used were given a high beta dose, then independent aliquots were annealed in air at a temperature varying from 300 degrees C to 900 degrees C. It has been observed that the TL growth with dose, after annealing and re-irradiation, evolved from a linear behaviour to a marked supralinear one according to annealing temperature linked respectively with a partial or a total thermal drainage of charges in deep traps. Consequently, during the TL-dating process of materials anciently heated at low temperature in the past (between 300 degrees C and 500 degrees C approximately), a special care has to be taken by adopting an annealing treatment that approaches the filling state of trapped charges that the samples had after the archaeological zeroing. This necessary new requirement strengthens accuracy and reliability of TL-dates obtained at Laugerie Haute.