Study of olivines from Omolon and Seymchan meteorites using X-ray diffraction and Mössbauer spectroscopy with a high velocity resolution

Study of olivine from Omolon and Seymchan meteorites was performed using X-ray diffraction and Mössbauer spectroscopy with a high velocity resolution. X-ray diffraction patterns were measured at room temperature while Mössbauer spectra were measured at 295 and 90 K. The orthorhombic crystal lattice parameters were evaluated for olivine from Omolon and Seymchan. These parameters appeared to be different for olivines from both meteorites. Mössbauer spectral components related to 57Fe in crystallographically non-equivalent sites M1 and M2 in both olivines were determined and its Mössbauer hyperfine parameters were evaluated. Some differences in the tendencies of temperature dependence of spectral parameters and small variations of 57Fe quadrupole splitting in both M1 and M2 sites of olivines from Omolon and Seymchan were found. On the basis of Mössbauer parameters and chemical data, the temperatures of equilibrium cation distribution were evaluated for both olivines. © 2012 American Institute of Physics

Evaluation of the Debye temperature for iron cores in human liver ferritin and its pharmaceutical analogue Ferrum Lek using Mossbauer spectroscopy

An iron polymaltose complex Ferrum Lek used as antianemic drug and considered as a ferritin analogue and human liver ferritin were investigated in the temperature range from 295K to 90K by means of 57Fe Mossbauer spectroscopy with a high velocity resolution i.e. in 4096 channels. The Debye temperatures equal to 502K for Ferrum Lek and to 461K for human liver ferritin were determined from the temperature dependence of the center shift obtained using two different fitting procedures.Comment: 13 pages, 5 figure

Irradiation of Fe-Mn Supersaturated Solid Solution with Ions of Various Atomic Masses (Ar+, Xe+) and Analysis of the Role of Nanosized Dynamic Effects in the Activation Processes of Long-Range Type

A multiple increase in the atom mobility in metastable supersaturated (quenched from 850 °C) Fe-8.16 at % Mn solid solution is detected at temperatures less than 250°C under irradiation with 5-keV Ar+ and Xe+ ions of different masses. The irradiation-induced atom redistribution in the entire volume of foils 30 μm thick at a projected Ar+ and Xe+ ion ranges as much as 20-30 nm only is found and studied by the transmission Mössbauer spectroscopy. Long-range effects at low irradiation doses and anomalously low temperatures are attributed to "radiation shaking" of metastable media with post-cascade solitary waves in contrast to thermally stimulated radiation-enhanced processes in the narrow nanoscale near-surface layers of the alloy. It has been shown that heavier Xe+ ions at higher irradiation doses have a stronger impact on the solid solution than Ar+ ions

Iron environment non-equivalence in both octahedral and tetrahedral sites in NiFe2O4 nanoparticles: study using Mössbauer spectroscopy with a high velocity resolution

Mössbauer spectrum of NiFe2O4 nanoparticles was measured at room temperature in 4096 channels. This spectrum was fitted using various models, consisting of different numbers of magnetic sextets from two to twelve. Non-equivalence of the 57Fe microenvironments due to various probabilities of different Ni2+ numbers surrounding the octahedral and tetrahedral sites was evaluated and at least 5 different microenvironments were shown for both sites. The fit of the Mössbauer spectrum of NiFe 2O4 nanoparticles using ten sextets showed some similarities in the histograms of relative areas of sextets and calculated probabilities of different Ni2+ numbers in local microenvironments. © 2012 American Institute of Physics

Comparative study of nanosized iron cores in human liver ferritin and its pharmaceutically important models Maltofer® and Ferrum Lek using Mössbauer spectroscopy

Studies of human liver ferritin and its pharmaceutically important models Maltofer® and Ferrum Lek were carried out using Mössbauer spectroscopy with a high velocity resolution at 295 and 90 K and Mössbauer spectroscopy with a low velocity resolution at 40 and 20 K. The Mössbauer spectra fits using a multi-component model confirm the hypothesis of the complicated heterogeneous structure of nanosized iron cores in the investigated samples. © 2013 Allerton Press, Inc

Mössbauer spectroscopy with a high velocity resolution applied for the study of meteoritic iron-bearing minerals

Mössbauer spectroscopy with a high velocity resolution was applied for study of iron-bearing minerals in different meteorites. The possibility of technique to reveal small variations in Mössbauer hyperfine parameters of the 57Fe in the non-equivalent M1 and M2 sites in olivines from Farmington L5 and Tsarev L5 ordinary chondrites and from Omolon and Seymchan pallasites was demonstrated. The necessity of accounting for the Fe and Ni occupation probabilities in the local microenvironments for non-equivalent sites M1, M2 and M3 in schreibersite, an iron nickel phosphide from Sikhote-Alin iron meteorite, in the fit of its Mössbauer spectra was shown. Variations in Mössbauer parameters of metal samples from visually different areas at the saw-cut surface of Chinga iron meteorite fragment with unknown origin were observed; these variations may be related to different metal phase composition and local variations of Ni concentration in the metal phases in these areas. © 2012 Elsevier B.V. All rights reserved

Variation of quadrupole splitting in modified oxyhemoglobin: A Mössbauer effect study

Human adult hemoglobin modified by both pyridoxal-5′-phosphate and glutaraldehyde in the oxy-form was studied by Mössbauer spectroscopy. Mössbauer spectra were measured at 87 and 295 K (hemoglobin in lyophilized form) and at 87 K (hemoglobin in frozen solution). The values of the quadrupole splitting for modified oxyhemoglobin were found to be lower then those of oxyhemoglobin without modifications in lyophilized form and frozen solution, respectively. The Mössbauer spectra of modified oxyhemoglobin were also analyzed in terms of the heme iron inequivalence in α- and β-subunits of the tetramer. Differences of the tendencies of temperature dependencies of quadrupole splitting for modified and non-modified oxyhemoglobin in lyophilized form were shown. Key words: Hemoglobin; Mössbauer Spectroscopy; Quadrupole Spitting.This work was supported in part by the Russian Foundation for Basic Research (grant # 97-04-49482)

Variations in quadrupole splitting of the 57Fe in the M1 and M2 sites of meteoritic olivines with different origin

A comparative study of meteoritic olivine in bulk samples of Farmington L5 and Tsarev L5 ordinary chondrites and extracted from Omolon and Seymchan the main-group pallasites was performed using Mössbauer spectroscopy with a high velocity resolution. Mössbauer spectra for each specimen were measured at 295 and 90 K. Mössbauer spectral components related to the 57Fe in crystallographically non-equivalent sites M1 and M2 in olivines were determined and their Mössbauer hyperfine parameters were evaluated. It was found small variations of quadrupole splitting for the 57Fe in both the M1 and M2 sites of olivines in bulk ordinary chondrites and olivines extracted from pallasites. © 2012 Springer Science+Business Media Dordrecht

An analysis of quadrupole splitting of the Mössbauer spectra of ferritin and iron-dextran complexes in relation to the iron core microstructural variations

Mössbauer spectra of human liver ferritin and some pharmaceutically important iron-dextran complexes as ferritin models were measured at 87 K (frozen solutions) and at both 87 and 295 K (lyophilized forms). The Mössbauer spectra consisted of paramagnetic doublets only. However, the spectral line shapes were not Lorentzian and these Mössbauer spectra were better fitted using a superposition of two or more quadrupole doublets or using a distribution of quadrupole splittings. The differences of the maximal quantity of quadrupole doublets for better fitting of various Mössbauer spectra of ferritin and iron-dextran complexes were compared with the fitting using the distribution of quadrupole splitting for additional analysis. It is possible that variations of the quantity of quadrupole doublets for better fitting of Mössbauer spectra of ferritin and iron-dextran complexes may be related to heterogeneous iron cores in the samples. This heterogeneity is supposed to be different for various samples and changed for lyophilized samples and for frozen solutions as well as for various temperatures