scholarly journals Mössbauer spectra of photosystem-I-reaction centres from the blue-green alga Chlorogloea fritschii

1979 ◽  
Vol 182 (3) ◽  
pp. 861-865 ◽  
Author(s):  
E H Evans ◽  
J D Rush ◽  
C E Johnson ◽  
M C W Evans
Keyword(s):  
Green Alga ◽  
Photosystem I ◽  
Mössbauer Spectra ◽  
Mossbauer Spectroscopy ◽  
Chemical Reduction ◽  
Blue Green Alga ◽  
Mossbauer Spectra ◽  
Maximum Reduction ◽  
Reaction Centres ◽  
Reduction Of Iron

Substantial amounts of iron have been shown by Mössbauer spectroscopy to be present in Photosystem-I preparations from the blue-green alga Chlorogloeta fritschii. Changes in the spectra on chemical reduction provide evidence that some of this iron is very similar to that found in the 4Fe-4S centres of ferredoxins. Such reduced samples also show e.p.r. signals consistent with maximum reduction of iron-sulphur centres A and B of Photosystem I. An unchanged component in the spectra indicates, assuming all centres A and B are reduced, the presence of another iron-containing species.

scholarly journals Iron Doped SBA-15 Mesoporous Silica Studied by Mössbauer Spectroscopy

2016 ◽  
Vol 2016 ◽  
pp. 1-6 ◽  
Author(s):  
Łukasz Laskowski ◽  
Magdalena Laskowska ◽  
Jerzy Jelonkiewicz ◽  
Tomasz Galkowski ◽  
Piotr Pawlik ◽  
...  
Keyword(s):  
Mössbauer Spectroscopy ◽  
Mesoporous Silica ◽  
Metal Ion ◽  
Density Functional ◽  
Mössbauer Spectra ◽  
Mossbauer Spectroscopy ◽  
Resonance Raman Spectroscopy ◽  
Resonance Raman ◽  
Mossbauer Spectra ◽  
Mößbauer Spectroscopy

Mesoporous silica SBA-15 containing propyl-iron-phosphonate groups were considered to confirm their molecular structure. To detect the iron-containing group configuration the Mössbauer spectroscopy was used. Both mesoporous silica SBA-15 containing propyl-iron-phosphonate groups and pure doping agent (iron acetylacetate) were investigated using Mössbauer spectroscopy. The parameters such as isomer shift, quadrupole splitting, and asymmetry in57Fe Mössbauer spectra were analyzed. The differences in Mössbauer spectra were explained assuming different local surroundings of Fe nuclei. On this base we were able to conclude about activation of phosphonate units by iron ions and determinate the oxidation state of the metal ion. To examine bonding between iron atoms and phosphonic units the resonance Raman spectroscopy was applied. The density functional theory (DFT) approach was used to make adequate calculations. The distribution of active units inside silica matrix was estimated by comparison of calculated vibrational spectra with the experimental ones. Analysis of both Mössbauer and resonance Raman spectra seems to confirm the correctness of the synthesis procedure. Also EDX elemental analysis confirms our conclusions.

Microstructure Evolution and Mossbauer Spectroscopy Research of Nanostructured Ni3 Fe Intermetallic

2021 ◽  
Vol 32 ◽  
pp. 1-13
Author(s):  
Amel Kaibi ◽  
Abderrahim Guittoum ◽  
Nassim Souami ◽  
Mohamed Kechouane
Keyword(s):  
Magnetic Field ◽  
Mössbauer Spectroscopy ◽  
Mössbauer Spectra ◽  
Milling Time ◽  
Mossbauer Spectroscopy ◽  
Hyperfine Magnetic Field ◽  
X Ray Diffraction ◽  
X Ray ◽  
Mossbauer Spectra ◽  
Mößbauer Spectroscopy

Nanocrystalline Ni75Fe25 (Ni3Fe) powders were prepared by mechanical alloying process using a vario-planetary high-energy ball mill. The intermetallic Ni3Fe formation and different physical properties were investigated, as a function of milling time, t, (in the range 6 to 96 h range), using X-Ray Diffraction (XRD) and Mössbauer Spectroscopy techniques. X-ray diffraction were performed on the samples to understand the structural characteristics and get information about elements and phases present in the powder after different time of milling. The refinement of XRD spectra revealed the complete formation of fcc Ni (Fe) disordered solid solution after 24 h of milling time, the Fe and Ni elemental distributions are closely correlated. With increasing the milling time, the lattice parameter increases and the grains size decreases. The Mössbauer experiments were performed on the powders in order to follow the formation of Ni3Fe compound as a function of milling time. From the adjustment of Mössbauer spectra, we extracted the hyperfine parameters. The evolution of hyperfine magnetic field shows that the magnetic disordered Ni3Fe phase starts to form from 6 h of milling time and grow in intensity with milling time. For the milling time more than 24 h, only the Ni3Fe disordered phase is present with a mean hyperfine magnetic field of about 29.5 T. The interpretation of the Mossbauer spectra confirmed the results obtained by XRD.

Electronic and magnetic states of Fe ions in the Co2FeBO5

2021 ◽  
Author(s):  
Natalia Kazak ◽  
Yurii V. Knyazev ◽  
Vyacheslav Zhandun ◽  
Juan Bartolomé ◽  
Ana Arauzo ◽  
...  
Keyword(s):  
Mössbauer Spectroscopy ◽  
Room Temperature ◽  
Mössbauer Spectra ◽  
Mossbauer Spectroscopy ◽  
57Fe Mössbauer Spectroscopy ◽  
57Fe Mössbauer ◽  
Mossbauer Spectra ◽  
57Fe Mossbauer Spectroscopy ◽  
Magnetic States ◽  
Fe Ions

The ludwigite Co2FeBO5 has been studied experimentally using 57Fe Mössbauer spectroscopy and theoretically by means of the DFT+GGA calculations. The room-temperature Mössbauer spectra are composed of four quadrupole doublets corresponding...

scholarly journals Mössbauer study of Fe phases in terrestrial olivine basalts from southern Egypt

Mineralogia ◽  
2013 ◽  
Vol 44 (1-2) ◽  
pp. 3-12 ◽  
Author(s):  
Kamaleldin M. Hassan ◽  
Julius Dekan
Keyword(s):  
Optical Microscopy ◽  
Crystal Chemistry ◽  
Mössbauer Spectra ◽  
Mossbauer Spectroscopy ◽  
X Ray Diffraction ◽  
Mössbauer Study ◽  
Hyperfine Parameters ◽  
X Ray ◽  
Mossbauer Spectra ◽  
Oxidized Iron

AbstractOlivine basalts from southern Egypt were studied by 57Fe Mössbauer spectroscopy at 297 and 77 K, and by optical microscopy and X-ray diffraction. The 57Fe Mössbauer spectra show three-magnetic sextets, three doublets of ferrous (Fe2+), and a weak ferric (Fe3+) doublet that is attributable to a nanophase oxide (npOx). The magnetic sextets relate to titanomagnetite and the Fe2+ doublets to olivine, pyroxene, and ulvöspinel. Variations in the hyperfine parameters of the various Fe components are attributed to changes in the local crystal chemistry. The intensity of oxidation (Fe3+/ΣFe) in the rocks varies from 20-27% with the oxidized iron largely residing in the titanomagnetite.

scholarly journals Mössbauer study of treated Nd2Fe14B

Nukleonika ◽  
2015 ◽  
Vol 60 (1) ◽  
pp. 7-10 ◽  
Author(s):  
Mieczysław Budzyński ◽  
Virgil C. Constantin ◽  
Ana-Maria J. Popescu ◽  
Zbigniew Surowiec ◽  
Tamara M. Tkachenka ◽  
...  
Keyword(s):  
Mössbauer Spectroscopy ◽  
Grain Boundaries ◽  
Mössbauer Spectra ◽  
Mossbauer Spectroscopy ◽  
Main Phase ◽  
Surface Material ◽  
Mössbauer Study ◽  
Water Solutions ◽  
Mossbauer Spectra ◽  
Neodymium Magnets

Abstract The Nd2Fe14B cylindrical magnets were treated with water solutions of alkali, acid, and salt. Mössbauer spectroscopy was applied to study the composition and properties of the surface material of the treated magnets. It is shown that the main phase of the permanent Nd2Fe14B magnet partly decomposes. The released α-Nd at the grain boundaries interacts with water and forms neodymium hydroxide matrix, and the released Fe diffuses into it. The presence of Fe-Nd(OH)3 is reflected in the paramagnet doublet in the Mössbauer spectra of treated neodymium magnets.

Mössbauer spectra of α- and γ-polymorphs of FeOOH and Fe2O3 : effects of poor crystallinity and of Al-for-Fe substitution

Clay Minerals ◽  
2002 ◽  
Vol 37 (4) ◽  
pp. 591-606 ◽  
Author(s):  
E. De Grave ◽  
C. A. Barrero ◽  
G. M. Da Costa ◽  
R. E. Vandenberghe ◽  
E. Van San
Keyword(s):  
Mössbauer Spectroscopy ◽  
Mössbauer Spectra ◽  
Mossbauer Spectroscopy ◽  
Precise Determination ◽  
Zero Field ◽  
Hyperfine Fields ◽  
Morin Transition ◽  
Mossbauer Spectra ◽  
Al Content ◽  
Mößbauer Spectroscopy

AbstractThis paper presents various aspects, revealed by Mössbauer spectroscopy, of structural and magnetic properties of Al-substituted small-particle soil-related oxides. For goethite we focus on the relations between the hyperfine fields on the one hand, and crystallinity and Al content on the other. It is argued that these relations only provide a rough estimate of the Al content in natural samples. The ferrimagnetic-like behaviour reflected in the external-field Mössbauer spectra (4.2 K, 60 kOe) of certain Al goethites is presented. The spectra obtained for lepidocrocites are not spectacular, but confirmed that up to ∼10 at.% Al can be incorporated in the structure. Three differently-made series of hematites are considered. The Morin transition and spin structures in hematite are very sensitive to crystallinity and Al content, and probably to the presence of structural OH–. Integral low-energy electron Mössbauer spectroscopy on non-substituted samples indicates that the Morin-transition temperature in the surface layers (2 to 5 nm) is not significantly shifted from the bulk value. Measurements in extremely high magnetic fields (140 kOe) have shown that a spin-flip transition is induced in highly-substituted samples which exhibit no Morin transition in zero field. The use of external fields is crucial for the characterization and precise determination of the hyperfine parameters and site occupancies for maghemites, and for phase analyses of magnetic soils.

119Sn Mössbauer spectroscopy of solvothermally synthesized fluorides ASnF3 (A = Na, K, Rb, Cs)

2015 ◽  
Vol 70 (10) ◽  
pp. 765-767
Author(s):  
Birgit Gerke ◽  
Thanh Thao Tran ◽  
Rainer Pöttgen ◽  
P. Shiv Halasyamani
Keyword(s):  
Mössbauer Spectroscopy ◽  
Quadrupole Splitting ◽  
Mössbauer Spectra ◽  
Mossbauer Spectroscopy ◽  
Lone Pair ◽  
Electric Quadrupole ◽  
119Sn Mössbauer Spectroscopy ◽  
Solvothermal Route ◽  
Mossbauer Spectra ◽  
Divalent Tin

AbstractThe complex Sn(II) fluorides ASnF3 (A = Na, K, Rb, Cs) were synthesized from the alkali fluorides and SnF2 in methanol through a solvothermal route. Their 119Sn Mössbauer spectra manifest divalent tin. The isomer shifts range from 3.09 to 2.94 mm s–1. The pronounced lone-pair character at the Sn(II) centres is expressed by strong electric quadrupole splitting (1.91–1.95 mm s–1). The two, respectively four crystallographically independent tin sites in NaSnF3, KSnF3 and RbSnF3 could not be resolved in the 119Sn spectra.

1,3,5-Trimethylbenzene(mesitylene) adducts with selected tin(II) compounds: the syntheses of Sn(SO3F)2•C9H12 and Sn(SbF6)2•2C9H12

1990 ◽  
Vol 68 (2) ◽  
pp. 350-355 ◽  
Author(s):  
D. Y. Gin ◽  
M. S. R. Cader ◽  
J. R. Sams ◽  
F. Aubke
Keyword(s):  
Mössbauer Spectroscopy ◽  
Chemical Analysis ◽  
Infrared Spectra ◽  
Mössbauer Spectra ◽  
Mossbauer Spectroscopy ◽  
Adduct Formation ◽  
High Yield ◽  
Mossbauer Spectra ◽  
Vibrational Study ◽  
Very High

Addition of 1,3,5-trimethylbenzene (mesitylene or mes) to the tin(II) salts, Sn(SO3F)2 and Sn(SbF6)2, results in the formation of adducts of the composition Sn(SO3F)2•mes and Sn(SbF6)2•2mes in very high yield. The adducts are characterized by chemical analysis and infrared spectra. The adduct formation is followed by 119Sn Mössbauer spectroscopy. It appears that only tin(II) compounds with large, weakly nucleophilic anions are capable of forming mesitylene adducts, while SnCl2, SnF2, and stannocene do not give any indication of adduct formation under similar conditions. Keywords: tin(II)–mesitylene complexes, synthesis, vibrational study, 119Mossbauer spectra.

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