Display omitted
► Mössbauer spectroscopy with a high velocity resolution. ► Methodological aspects. ► Advances in biomedical, pharmaceutical, cosmochemical and nanotechnological research.
The ...methodological principles of velocity resolution as additional characteristic of the quality of both Mössbauer spectrometer velocity driving system and Mössbauer spectrum were briefly considered. Significantly better quality of Mössbauer spectra measured with a high velocity resolution in comparison with those measured with a low velocity resolution was demonstrated. The main advances of recent studies of iron containing biomolecules, pharmaceutical products, meteorite samples and nanoparticles using Mössbauer spectroscopy with a high velocity resolution were considered and advantages of this technique were shown.
A brief review on the applications of Mössbauer spectroscopy in biomedical research discusses the results of more than fifty years of experience in this field. Basing on the numerous results the main ...directions of biomedical applications of Mössbauer spectroscopy are considered as follows: 1) studies of the quantitative changes of iron-containing biomolecules related to pathological processes; 2) studies of the qualitative changes in iron-containing biomolecules related to pathological processes; 3) studies of the effect of various environmental factors (physical, chemical, and biological) on iron-containing biomolecules; 4) studies of metabolic processes by means of analysis of the Mössbauer nuclides pathways in organisms; 5) studies of dynamic processes; 6) studies of pharmaceutical compounds and blood substitutes containing Mössbauer nuclides; 7) miscellaneous studies. Some examples of biomedical research using
57
Fe,
57
Co,
119
Sn,
153
Sm, and
197
Au Mössbauer nuclides are presented.
Application of thin reference absorbers namely α-Fe foil, sodium nitroprusside, potassium ferricyanide and potassium ferrocyanide for testing and control of the velocity driving system in the ...high-quality and -sensitivity Mössbauer spectrometers is demonstrated. The deviation of the absorption line from Lorentzian shape may be considered as indicator of the velocity driving system being out-of-tune. Such an estimation of the differential nonlinearity of the velocity ranges is much more sensitive than that by laser interferometer. This testing and control of the velocity driving system provide the measurements of high-quality and precision Mössbauer spectra and avoid getting the poor spectra with obtaining artifact results.
The bulk interior of Kemer L4 ordinary chondrite was characterized for the first time by means of optical microscopy, scanning electron microscopy with energy dispersive spectroscopy, Raman ...spectroscopy, X-ray diffraction, magnetization measurements and Mössbauer spectroscopy with a high velocity resolution. The main and minor iron-bearing phases were found as well as ferrihydrite as a result of weathering. The Fe2+ partitioning among the M1 and M2 sites in olivine, orthopyroxene and clinopyroxene was determined from the X-ray diffraction. The ratios of Fe2+ occupancies for these crystals were estimated from both X-ray diffraction and Mössbauer spectroscopy data and appeared to be in a good agreement. The distribution coefficients KD and the temperatures of equilibrium cation distribution Teq were also evaluated for olivine and orthopyroxene from two independent techniques and were in a good consistence: KD = 1.77, Teq = 441 K (X-ray diffraction) and KD = 1.77, Teq = 439 K (Mössbauer spectroscopy) for olivine and KD = 0.10, Teq = 806 K (X-ray diffraction) and KD = 0.09, Teq = 787 K (Mössbauer spectroscopy) for orthopyroxene. The fusion crust of Kemer L4 was studied using X-ray diffraction, magnetization measurements and Mössbauer spectroscopy. Magnesioferrite and probably maghemite were found in the fusion crust in addition to other phases observed in the bulk interior.
Display omitted
•Raman spectra of orthopyroxene in Kemer L4 indicate 13–20 mol% of ferrosilite.•Kemer L4 ZFC curve shows two magnetic phase transitions for chromite at 62 and 52 K.•Fe2+ occupancies of the M1 and M2 sites in silicates agree for XRD and Mössbauer data.
Iron(III)-polymaltose pharmaceutical ferritin analogue Ferrifol® was investigated by high resolution transmission electron microscopy (HRTEM), X-ray diffraction, thermogravimetry, electron magnetic ...resonance (EMR) spectroscopy, direct current magnetization measurements and 57Fe Mössbauer spectroscopy to get novel information about the structural arrangement of the iron core. The Ferrifol® Mössbauer spectra measured in the range from 295 K to 90 K demonstrated non-Lorentzian two-peak pattern. These spectra were better fitted using a superposition of 5 quadrupole doublets with the same line width. The obtained Mössbauer parameters were different and an unusual line broadening with temperature decrease was observed. Measurements of the Ferrifol® Mössbauer spectra from 60 K to 20 K demonstrated a slow decrease of magnetic relaxation in the iron core. Zero-field-cooled and field-cooled magnetization measurements revealed a blocking temperature at ~33 K and a paramagnetic state of the Ferrifol® iron core at higher temperatures. Isothermal magnetization measurements at 5 K show that the saturation magnetic moment is ~0.31 emu/g. X-band EMR spectroscopy measurements revealed the presence of different magnetic species in the sample. Transmission electron microscopy demonstrated that the size of the iron cores in Ferrifol® is in the range 2–6 nm. The lattice periodicity in these iron cores, measured on the HRTEM images, vary in the range 2.2–2.7 Å. This can be best understood as sets of close packed O(OH) layers in ferrihydrite cores without long range correlation.
The Mössbauer spectra of iron(III)-polymaltose pharmaceutical ferritin analogue Ferrifol® (T=295–90 K) were fitted using five quadrupole doublets. The blocking temperature for the largest iron cores is 33 K. High resolution transmission electron microscopy shows the lattice periodicity in the Ferrifol® iron cores in the range 2.2–2.7 Å. Display omitted
•Ferrifol® is an iron(III)-polymaltose pharmaceutical ferritin analogue.•Magnetization measurements of Ferrifol® demonstrate a blocking temperature at ~33 K.•The lattice periodicity in the Ferrifol® iron cores varies in the range 2.2–2.7 Å.
The meter-scale variations of material properties of the 20-m sized Chelyabinsk meteoroid are critical for understanding why the meteoroid fragmented the way it did and caused the devastating ...airburst that sent over 1600 people to the hospital for treatment of glass cuts and minor injuries on February 15, 2013. From a range of differently looking unweathered meteorite fragments that were recovered shortly after the event, these material differences were probed by means of optical and scanning electron microscopy, X-ray diffraction (XRD), and the high velocity resolution Mössbauer spectroscopy. All main and some minor iron-bearing phases were identified on the basis of XRD data and Mössbauer spectra. The Fe2+ partitioning between the M1 and M2 sites in silicate phases was determined independently using XRD and Mössbauer data. Different meteorite fragments show a range of 570–1180 K in the temperature of the Fe2+ and Mg2+ equilibrium distribution between the M1 and M2 sites in olivine, while that in orthopyroxene falls in the range 870–1180 K (these ranges were estimated using both techniques). This fact points out a slightly different thermal history of these minerals before they accumulated in different parts of the Chelyabinsk meteoroid. The Chelyabinsk meteoroid is a fragmental breccia from materials formed at different depths in their parent body, or from materials that experienced different annealing temperatures in impacts. In addition, the fusion crust from two fragments, studied by XRD and Mössbauer spectroscopy, experienced a different thermal history during entry, suggesting that the fragment with mixed light and dark lithologies was located deeper inside the initial meteoroid than the fragment with only light lithology, or fragmented less readily.
Mössbauer spectrum of Chelyabinsk LL5 fragment No 2 (left) and differences in the total relative areas for the Mössbauer spectral components corresponding to iron-bearing minerals (variations in the relative iron content in these minerals) for different fragments of Chelyabinsk LL5 meteorite: No 1 and No 1a with light lithology, No 2 and No 2a with mixed light and dark lithologies and No 3 with black lithology: Ol – olivine, OPy – orthopyroxene, CPy – clinopyroxene, Tr – troilite, Chr – chromite, Her – hercynite, Ilm – ilmenite, M – metallic iron alloy (right). Display omitted
•The internal differences on a meter-size scale in the 20-m sized Chelyabinsk meteoroid•Physical properties of different Chelyabinsk meteoroid fragments•Different thermal histories of silicates in different parts of the Chelyabinsk meteoroid
Magnesium ferrite (MgFe2O4) was synthesized using the solution combustion method. The concentration of the fuel was varied and investigated its effect on spectroscopic, structural and magnetic ...properties of MgFe2O4 nanoparticles. The XRD pattern showed a decrease in the crystallite size and increase in the lattice strain, dislocation density and specific surface area upon increasing the fuel amount. The shift in the FTIR band (~434 cm–1) corresponds to the Fe–O vibration in the octahedral sites. The values of HC decreased while Mr values increased continuously with the increase of the fuel concentration. The Mössbauer spectra of MgFe2O4 nanoparticles measured with a high velocity resolution demonstrated a large number of magnetic sextets assigned to the tetrahedral (A) and octahedral B sites. These magnetic sextets were considered as a result of different Fe3+ local microenvironments depending on Mg2+ cations distributions among the neighboring (A) and B sites. The calculations of binomial distribution of the probabilities of the numbers of Mg2+ cations within the sphere of 3.7 Å around Fe3+ cations in both (A) and B sites demonstrated distributions of different probabilities for these sites in agreement with the Mössbauer spectra fits. The numbers of magnetic sextets and their hyperfine parameters assigned to the (A) and B sites were found slightly varied for MgFe2O4 nanoparticles prepared with different fuel concentrations.
Display omitted
•The values of HC decreased while Mr values increase with fuel concentration increase.•The Mössbauer spectra demonstrate many sextets assigned to both (A) and B sites.•The different numbers of Mg2+ around Fe3+ in both (A) and B sites were calculated.
Ordinary chondrites from H, L and LL groups were studied using Mössbauer spectroscopy with a high velocity resolution. Mössbauer parameters of spectral components were obtained using new fitting ...model excluding the effect of previous misfits of troilite component. Obtained parameters were related to corresponding iron-bearing minerals in ordinary chondrites. The differences of these minerals content as well as small differences in the hyperfine parameters of the same iron-bearing minerals were revealed for different meteorites. The temperatures of equilibrium cations distribution in silicates were estimated and suitable parameters for classification of H, L and LL chondrites were supposed using Mössbauer parameters.
Display omitted
•Mössbauer spectra of H, L and LL ordinary chondrites with a high velocity resolution•New fitting model for Mössbauer spectra of ordinary chondrites•Comparison of Mössbauer parameters for iron-bearing minerals in ordinary chondrites•Classification of H, L and LL chondrites using Mössbauer parameters
We studied the interior and the fusion crust of the recently recovered Ozerki L6 meteorite using optical microscopy, scanning electron microscopy (SEM) with energy dispersive spectroscopy, X‐ray ...diffraction (XRD), magnetization measurements, and Mössbauer spectroscopy. The phase composition of the interior and of the fusion crust was determined by means of SEM, XRD, and Mössbauer spectroscopy. The unit cell parameters for silicate crystals were evaluated from the X‐ray diffractograms and were found the same for the interior and the fusion crust. Magnetization measurements revealed a decrease of the saturation magnetic moment in the fusion crust due to a decrease of Fe‐Ni‐Co alloy content. Both XRD and Mössbauer spectroscopy show the presence of magnesioferrite in the fusion crust. The temperatures of cation equilibrium distribution between the M1 and M2 sites in silicates calculated using the data obtained from XRD and Mössbauer spectroscopy appeared to be in a good consistency: 553 and 479 K for olivine and 1213 and 1202 K for orthopyroxene.
Iron‐bearing phases in the impact melt rock (impactite) from Jänisjärvi astrobleme (Karelia, Russian Federation) were studied by optical microscopy, electron probe microanalysis, Raman spectroscopy, ...X‐ray diffraction, and 57Fe Mössbauer spectroscopy. The phase composition and the contents of elements were determined in the studied impactite. The Raman spectra of cordierite, chamosite, and ilmenite in the impact melt rock were measured and analyzed. The 57Fe Mössbauer spectrum of Jänisjärvi impactite demonstrated the presence of different iron microenvironments in the iron‐bearing phases in the impact melt rock, which were assigned to cordierite; the M1, M2, M3, and M4 sites in chamosite; ilmenite; and ferrihydrite.
PDF
