Search results for "Mössbauer Spectroscopy"
showing 10 items of 364 documents
A CEMS/AES study of the passivation of iron
1989
The passivation of iron and steel (DIN 1623) was studied by integral and depth selective conversion electron Mossbauer spectroscopy and Auger electron spectroscopy. Thickness and phase composition of the passive layer formed in sulphate solution and in a phosphate buffer were determined in dependence on the anodic potential and the duration of the passivating procedure. The experimental results lead to the conclusion that not the whole oxidic layer is responsible for the passivity but only a very thin intermediate layer formed between the cubic substrate and the rhombic oxide (γ-FeOOH) cover.
A corrosion study of austenitic and martensitic steels under boiler conditions by means of 57Fe conversion electron mössbauer spectroscopy
1978
Abstract The growth of protective oxide layers on a martensitic FeCr (1.4122) and two austenitic FeCrNi steel samples (1.4550 and Incoloy 800) was studied by means of the 57Fe Conversion Electron Mossbauer Spectroscopy (CEMS). Scanning electron microscopy was applied to characterize the topographical nature of the oxide layers. Following a technical procedure of running-in steam generators, the steel specimens were oxidized in oxygen-free water at 295°C, 142 bar and a pH value between 9 and 10 for periods up to 70 h. In the case of the steels 1.4122 and 1.4550 the only oxide phase detected was non-stoichiometric magnetite, whereas nickel ferrite of nonstoichiometric composition was found…
Synthesis and structural studies by infrared and Mössbauer spectroscopy of adducts of tin(IV) and organotin(IV) derivatives with 2,2′-azopyridine
1985
Abstract A number of complexes have been prepared by the reaction between 2,2′-azopyridine(AZP) and tin(IV) halides and organotin(IV) halides, and characterized by elemental analysis and infrared and variable temperature 119Sn Mossbauer spectroscopies. All of the new compounds have 1:1 stoichiometry, with the AZP ligand occupying two coordination sites by bonding through one of the ring and one of the azo group nitrogen atoms, to give rise to distorted octahedral structures. In the diorganotin complexes the two organic groups occupy trans positions. The infrared and Mossbauer spectroscopic data suggest that these compounds are monomeric in the solid state.
Fe Mossbauer spectroscopy as a tool in astrobiology
2006
The element Fe and Fe-bearing minerals occur ubiquitously throughout the field of astrobiology. Cycling between the various oxidation states of Fe provides a source of energy available for life. Banded iron formations may record the rise of oxygenic photosynthesis. The distribution of Fe between Fe-bearing minerals and its oxidation states can help to characterize and understand ancient environments with respect to the suitability for life by constraining the primary rock type and the redox conditions under which it crystallized, the extent of alteration and weathering, the type of alteration and weathering products, and the processes and environmental conditions for alteration and weatheri…
Diorganotin(IV) N-acetyl-L-cysteinate complexes: synthesis, solid state, solution phase, DFT and biological investigations.
2009
Diorganotin(IV) complexes of N-acetyl-L-cysteine (H(2)NAC; (R)-2-acetamido-3-sulfanylpropanoic acid) have been synthesized and their solid and solution-phase structural configurations investigated by FTIR, Mössbauer, (1)H, (13)C and (119)Sn NMR spectroscopy. FTIR results suggested that in R(2)Sn(IV)NAC (R = Me, Bu, Ph) complexes NAC(2-) behaves as dianionic tridentate ligand coordinating the tin(IV) atom, through ester-type carboxylate, acetate carbonyl oxygen atom and the deprotonated thiolate group. From (119)Sn Mössbauer spectroscopy it could be inferred that the tin atom is pentacoordinated, with equatorial R(2)Sn(IV) trigonal bipyramidal configuration. In DMSO-d(6) solution, NMR spectr…
Synthesis and characterization of Sn(IV) complexes of lower rim 1,3-diacid derivative of calix[4]arene and their protective effects on tissue oxidati…
2005
The two Sn(IV) complexes synthesized using calix[4]arene-1,3-di-acid derivative were characterized by analytical, 1H, 13C and 119Sn NMR, matrix assisted laser desorption ionization mass, and 119Sn Mossbauer techniques and found that the complexes are tetranuclear possessing structurally two different types of tin centers. These complexes were evaluated for their protective value against blood and tissue oxidative stress in lead exposed male albino rats of Wistar strain. The results suggest that the two tin complexes significantly protect changes in lead induced biochemical variables indicative of heme synthesis pathway and exhibit only moderate effect on tissue oxidative stress. The benefic…
Variable-temperature X-ray crystal structure determinations of {Fe[tren(6-Mepy)3]}(ClO4)2and {Zn[tren(6-Mepy)3]}(ClO4)2compounds: correlation of the …
2007
Variable-temperature X-ray crystal structure determinations (80–330 K) on compounds {Fe[tren(6-Mepy)3]}(ClO4)2(1-Fe) {tren(6-Mepy)3is tris[3-aza-4-(6-methyl-2-pyridyl)but-3-enyl]amine} and {Zn[tren(6-Mepy)3]}(ClO4)2(1-Zn) {tren(6-Mepy)3is tris[3-aza-4-(6-methyl-2-pyridyl)but-3-enyl]amine} were carried out together with a detailed analysis of the unit-cell volume and parameters in the spin transition region for (1-Fe). Both compounds crystallize in the monoclinic system and retained the space groupP21/cat all measured temperatures. The Fe and Zn atoms are surrounded by six N atoms belonging to imine groups and pyridine groups of the trifurcated ligand, adopting a pseudo-octahedral symmetry. …
Soft-Chemical Growth ofγ-FeO(OH) Films on Self-Assembled Monolayers of Substituted Alkylthiols on Gold(111)
1999
Mathematical Evaluation of Mössbauer Spectra
1978
As in many other spectroscopic methods, it is necessary in Mossbauer spectroscopy to determine the positions, intensities or areas of the absorption and emission lines as accurately as possible. In the case of poorly resolved or complex hyperfine spectra due to different chemical species or several lattice sites in the sample it is not possible to evaluate the Mossbauer spectra just by hand. In addition, often one is faced with the problem of taking into account cosine smearing effects (Sec. 4.2), thick absorbers associated with the calculation of the transmission integral (Sec. 3.5), magnetic or electric relaxation (Sec. 6.7), or delayed coincidence Mossbauer measurements (Sec. 3.5), which…
Di-n-octyltin(IV) complexes with 5-[(E)-2-(aryl)-1-diazenyl]-2-hydroxybenzoic acid: Syntheses and assessment of solid state structures by 119Sn Mössb…
2007
Abstract Reactions of 5-[( E )-2-(aryl)-1-diazenyl]-2-hydroxybenzoic acids (LHH′, where the aryl group is an R-substituted phenyl ring such that for L 1 HH′: X = H; L 2 HH′: X=2′-OCH 3 ; L 3 HH′: X = 3′-CH 3 ; L 4 HH′: X = 4′-CH 3 ; L 5 HH′:X = 4′-Cl) with n Oct 2 SnO in 2:1 and 1:1 molar ratios have been investigated. Two types of complexes, n Oct 2 Sn(LH) 2 and {[ n Oct 2 Sn(LH)] 2 O} 2 , were isolated and they have been characterized by 1 H, 13 C, 119 Sn NMR, ESI-MS, IR and 119m Sn Mossbauer spectroscopic techniques in combination with elemental analyses. The crystal structures of n Oct 2 Sn(L 1 H) 2 ( 1 ), {[ n Oct 2 Sn(L 2 H)] 2 O} 2 ( 3 ) and {[ n Oct 2 Sn(L 3 H)] 2 O} 2 ( 4 ) were de…