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EMR study and superposition model analysis of Cr3+ and Fe3+ impurity ions in mullite powders used in aerospace industry

Stefaniuk I., Rogalska I..

Nukleonika

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2015

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Vol. 60, No. 3, part 1

399--403

EN

In this work, the electron magnetic resonance (EMR) spectra of the mullites powders were measured for different grain sizes (0.07 and 0.12 mm). We have used EMR spectroscopy at X-band, combined with superposition model (SPM) calculations to reveal electronic structure and establish correlations between structure, and surroundings of these complexes.

2

Study on organic radicals giving rise to multicomponent EMR spectra in dried fruits expose to ionizing radiation II. D-Glucose

Guzik G. P., Stachowicz W.

Nukleonika

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2013

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Vol. 58, No. 3

425--428

EN

Crystalline D-glucose extracted from dried resins was irradiated with 60Co gamma rays. The multicomponent EMR spectra of the samples kept at ambient temperature were compared with those heated at 105°C – the temperature close to the melting point of glucose. Normalized EMR spectra recorded with both samples were subtracted, resulting in a differential EMR spectrum. Spectral analysis of all three spectra has been done resulting in the identification of isotropic doublet of doublets assigned to less stable radical derived from parent glucose molecule.

3

Modelling of EMR data for Fe2+(S=2) ions in a [2Fe-2S] cluster in the reduced ferredoxin

Rudowicz Cz., Piwowarska D., Gnutek P.

Nukleonika

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2013

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Vol. 58, No. 3

347--350

EN

The modelling techniques employed in this study utilize structural data to enable correlation of EMR data – described by the spin Hamiltonian (SH) and optical spectroscopy data – described by the crystal field (CF) Hamiltonian. These techniques enable also to predict magnetic and spectroscopic properties of 3dN ions, especially 3d4 and 3d6 ions, in various systems. Specific applications are considered for [Fe2+ and Fe3+] binuclear centres in [2Fe-2S] cluster in the reduced ferredoxin and related biological molecules. The background for model calculations of the zero-field splitting (ZFS) parameters and/or crystal field parameters and the capabilities of the two major techniques used will be presented in the full paper. Here, we present preliminary results of the microscopic spin Hamiltonian (MSH) modelling for Fe2+ (3d6) ions in the reduced ferredoxin.

4

Higher - order field - dependent terms in spin Hamiltonians for transition ions : implications for high - magnetic field and high - frequency EMR measurements

Rudowicz Cz.

Nukleonika

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2013

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Vol. 58, No. 3

341--345

EN

An overview of theoretical background of the higher-order field-dependent (HOFD) terms in the generalized spin Hamiltonians for transition ions and current status of experimental studies of the HOFD terms is provided in the nutshell. The terms nonlinear in the magnetic field (B) of the type: B2S2, B3S, B5S or B2I2, B3I, B5I, where S and I is the electronic and nuclear spin, respectively, are of particular importance as compared with the usual linear Zeeman term B.g.S. This is due to the high B values, up to 100 T (pulsed fields), achievable at present in the high-magnetic field and/ or high-frequency electron magnetic resonance (HMF-EMR) measurements of magnetic and spectroscopic properties. A blueprint for future theoretical and experimental studies of the HOFD terms is proposed taking into account their implications for HMF-EMR measurements

5

A review of phase transitions in RbIn-molybdate

Zapart M. B., Zapart W.

Nukleonika

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2013

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Vol. 58, No. 3

365--370

EN

The paper gives a brief review of the results of EPR temperature studies of RbIn(MoO4)2 crystal. A sequence of several structural phase transitions has been found in this crystal in the temperature region 84–163 K. The transition at T1 = 163 K leads to an incommensurate triply modulated state, whereas ferroelastic phases start below T2 = 143 K. All the low temperature phases in the temperature region 84–143 K are examples of simultaneously ferroelastic and incommensurate ones. The transition observed at T5 = 84 K seems to suppress the ferroelastic properties of the crystal.