The Debye-Waller factor of molecules trapped in the pores of thirsty glass

Liquids and solutions containing Mössbauer active isotopes when trapped in the capillaries of porous silicate glasses show the Mössbauer effect¹ also at room temperature^2,3. A model is given for the explanation of this phenomenon.     

Mössbauer and X-ray diffraction study of an aluminium-magnesium-silicon alloy containing Pb and Sn

The Mössbauer parameters of tin in aluminium matrix were studied and published in an earlier paper¹. The aim of this work was to carry out investigations on tin in an aluminium alloy containing magnesium, silicon and lead beside the Mössbauer active tin. The effect of heat treatments on the formation of intermetallic compounds was studied by X-ray diffraction and by the Mössbauer spectra of¹¹⁹Sn.     

Emission Mössbauer spectroscopic studies on mixed-valence states of57Fe atoms produced in57Co-labeled trinuclear cobalt-iron carboxylates

Mixed-valence states of⁵⁷Fe-atoms produced after EC-decay of⁵⁷Co in oxo-centered trinuclear cobalt-iron carboxylates have been studied by means of emission Mössbauer spectroscopy. The emission Mössbauer spectra show nearly the same temperature dependence of the mixed-valence state as found in the absorption Mössbauer spectra of the corresponding trinuclear iron carboxylates. The results indicate that most of the decayed atoms keep their position at the sites of original⁵⁷Co atoms.     

A study of thin surface layers by multilayer Mössbauer spectroscopy /MMS/

A stacking Mössbauer technique, MMS has been applied for studying thin surface layers. The surface layers formed on the⁵⁷Fe film in aqueous solutions of corrosion inhibitors, such as zinc phosphate and barium metaborate, and in distilled water was studied by this method. It has been found that the corrosion is much slower in the presence of zinc phosphate and barium metaborate. XPS analysis suggests the formation of a mixed iron zinc phosphate on the surface of the⁵⁷Fe film after corrosion in a zinc phosphate solution.     

Mössbauer spectra of dimethenylbiferrocenediamine compounds

Summary ⁵⁷Fe Mössbauer studies of mono- and dibiferrocene derivatives and their triiodide salts of oxidized ferrocene derivatives show that there are small changes in the isomer shift and quadrupole splitting of these compounds. The mixed valence salt of dimethenylbiferrocenyl-p-phenylene-diamine is localized within the Mössbauer timescale.     

Characterization of silica supported Rh-Fe catalysts by Mössbauer technique

Silica supported Rh–Fe catalysts were characterized by means of in situ⁵⁷Fe Mössbauer spectroscopy. The Mössbauer spectra indicated that iron on the silica support existed either as Fe/O/ in the Rh–Fe alloy or as Fe³⁺ in Rh–Fe metal cluster compounds. The (Fe³⁺/Fe/O/) ratio and Mössbauer parameters were found to depend on the (Fe/Rh) atomic ratio in the catalysts. Such dependence corresponded to the change of catalytic properties of the supported Rh–Fe catalyst with the varying (Fe/Rh) ratio.     

Mössbauer study of hydrogenated Fe-Zr amorphous alloys

The effect of electrochemical hydrogenation was investigated in Fe₉₀Zr₁₀ and Fe₈₉Zr₁₁ amorphous alloys by means of⁵⁷Fe Mössbauer spectroscopy. Significant changes in the Mössbauer spectra as well as in the hyperfine field distribution of hydrogenated samples were found with increasing hydrogen concentration. It was established that the dependence of Curie temperature on hydrogen content had a maximum, and the hydrogen had two mean localization sites. By comparing the Mössbauer spectra of hydrogenated samples as-quenched and annealed before hydrogenation it was shown that low-temperature relaxation processes were going on at aging temperature as low as 150°C in this amorphous alloy and the low-temperature relaxation processes modify the localization of hydrogen. The combination of the hydrogenation and Mössbauer techniques gives a very sensitive method for detecting structural changes.     

User-friendly software for Mössbauer spectrum analysis

A new user-friendly software for analysis of Mössbauer-spectra has been developed. The program makes use of the advantages provided by the current generation of fast personal computers. An Evolution Algorithm^1,2 is used for global search of Mössbauer parameters in order to enhance the reliability of the obtained results. Fitting of Lorentzians, Pseudo-Voigt line profiles, and deriving hyperfine-field distributions including correlations and combinations and Mössbauer Line Sharpening by Fourier transformation provide a wide range of applicability.     

Quantitative multielemental analysis of titaniferous magnetites

Two representative titaniferous magnetite samples procured from Moulabhanj, Orissa, India have been studied by PIXE, EDXRF, Mössbauer spectroscopy, and XRD techniques. Major iron-bearing phases identified in the samples by Mössbauer spectroscopy and XRD are magnetite, hematite, ferrous ilmenite and ferric ilmenite. The Fe²⁺/Fe³⁺ ratio and the relative percentages of different minerals were determined from the resonance areas of Mössbauer spectra. Quantitative multielemental analysis was carried out by energy dispersive X-ray fluorescence (EDXRF) and proton induced X-ray emission (PIXE). Nineteen minor and trace elements have been quantified by EDXRF whereas by PIXE eighteen elements have been analyzed quantitatively. Concentrations of trace elements determined by EDXRF and PIXE were used in interpreting the physico-chemical condition of the depositional basin.     

Mössbauer and X-ray analysis of corrosion products from surface equipment of oil production well

Wellhead equipment corrosion samples including internal surface of choke were analyzed by means of Mössbauer spectroscopy and X-ray diffractometry. The samples include some impurities of quartz, dolomite and calcite. The resulted analysis shows some iron oxides and oxyhydroxides as surface equipment corrosion products.     

Determination of α and f for k0-NAA in irradiation sites with high thermalized neutrons

We have measured the ⁵⁷Fe Mössbauer spectra of the Hofmann pyridine complex Fe(pyridine)₂Ni(CN)₄ sample before and after exposure to high pressure of gaseous xenon. The temperature dependence of the high spin molar fraction has been determined from the ⁵⁷Fe Mössbauer spectra. The spin transition of the sample without the high pressure treatment occurs between 175 and 220 K with a hysteresis width of 15 K. Although the ⁵⁷Fe Mössbauer spectra suggest that the spin crossover behavior of the sample before and after the high pressure treatment are almost the same, the hysteresis of the latter sample is somewhat larger.     

Initial 119Sn Mössbauer Spectroscopy and X-ray Diffractometry Investigations of Electrodeposited Tin-Chromium and Tin-Zinc-Chromium Alloys

¹¹⁹Sn conversion electron Mössbauer spectroscopy, X-ray diffractometry and energy dispersive X-ray analysis (EDAX) were employed to investigate microstructure, composition and phases present in as-electroplated Sn-Cr and Sn-Cr-Zn alloys deposited on copper substrates. In the Sn-Cr deposits Cu, -Sn, Cr-Sn phases can be identified by X-ray diffractometry. The phase composition is significantly different between the samples prepared with relatively higher and lower current densities. In the diffractograms of Sn-Cr-Zn deposits Cu, -Sn, Zn phases can be well identified. A small intensity amorphous peak is also present, which can perhaps be associated with the presence of some amorphous Zn and Sn alloy. ¹¹⁹Sn Mössbauer spectra of Sn-Cr deposits exhibit an asymmetric broad main line centered near the isomer shift characteristic of -Sn as well as they contain a small component near the zero velocity which can be attributed to a SnO₂ phase based upon its characteristic. ¹¹⁹Sn Mössbauer spectra of Sn-Cr-Zn deposits are roughly similar to those of Sn-Cr deposits although the Mössbauer parameters of the third phase are different and vary with the Zn content. The presence of SnO₂ on the surface mainly in the Sn-Cr samples can be attributed to the corrosion process in the air.     

129I-Mössbauer spectroscopic studies of ferricinium,biferrocenium and 1′, 1′'-dihalobiferrocenium iodides

¹²⁹I-Mössbauer spectroscopic data are presented for the titled iodides. Comparison of Mössbauer parameters of the mixed-valence biferrocenium iodides suggests that the rate of intramolecular electron transfer depends on the nature of biferrocenium cation moiety in solid state.     

Mössbauer characterization of tin triflate Sn(OTf)2

¹⁵¹Sn Mössbauer spectroscopy was performed with tin triflate Sn(OTf)₂ in order to determine its Mösbauer parameters for analytical purposes. The typical Mössbauer parameters at 80 K for crystalline Sn(OTf)₂ are IS=4.01±0.02 mm/s and QS=1.20±0.04 mm/s and show that the stannous ion is at a site with less than cubic symmetry under perturbation of the crystal field effect.     

Mössbauer, vibrational spectroscopic and solution X-ray diffraction studies of the structure of iron(III) complexes formed with indole-3-alkanoic acids in acidic aqueous solutions

The chemical reactions between iron(III) and indole-3-acetic (IAA), -propionic (IPA), and -butyric (IBA) acids were studied in acidic aqueous solutions. The motivation of this work was that IAA is one of the most powerful natural plant-growth-regulating substances (phytohormones of the auxin series). Mössbauer spectra of the frozen aqueous solutions of iron(III) with indole-3-alkanoic acids as ligands (L), showed parallel reactions between Fe³⁺ and the ligands. Partly, it resulted in a complex formation which precipitated in aqueous solution and partly, in a redox process with iron(II) and the oxidised indole-3-alkanoic acids as products. The Mössbauer parameters of the Fe²⁺ species suggested a hexaaquo coordination environment. The chemical composition and coordination structure of the precipitated complexes were investigated using elemental analysis, Mössbauer spectroscopy, Fourier transform infrared (FTIR) and Raman spectroscopic techniques. The complexes were soluble in some organic solvents. So, Mössbauer, FTIR and solution X-ray diffraction measurements were carried out on the solution of complexes in acetone, hexadeutero acetone and methanol, respectively. The data obtained supported the existence of the μ-dihydroxo-bridging structure of the dimer: [L₂Fe<(OH)₂>FeL₂] (where L is indole-3-propionate, -acetate or -butyrate).     

Study of substituted pentacyanoferrate /II/ complexes by Mössbauer spectroscopy

The⁵⁷Fe Mössbauer spectra of substituted pentacyanoferrate /II/ complexes [/CN/₅ Fe^II L]^3– have been obtained for L=adenine, guanine, purine, caffeine, ethylene sulphide, dimethyl sulphoxide, and ammonia. The Mössbauer parameters are utilized to classify the various ligands according to their and bonding abilities. A linear correlation between the Mössbauer isomer shift and the tetragonal distortion caused by the ligand L is proposed. Comparison between this linear correlation and the approximative method of Wentworth and Piper¹ is made.     

57Fe Mössbauer spectroscopic characterisation of a ferromanganese nodule from the Central Indian Ocean

The iron bearing phases present in a ferromanganese nodule from the Central Indian Ocean have been determined using⁵⁷Fe Mössbauer spectroscopy. The Mössbauer results have been corroborated by XRD, IR and TG-DTA studies. The Mössbauer spectrum of a ferromanganese nodule shows a broad line width which indicates the presence of more than one iron bearing paramagnetic oxide or oxyhydroxide phases where iron is present as Fe³⁺. -FeOOH has been distinctly characterised as one of the iron bearing phases in the nodule. Other oxyhydroxide and oxide phases of iron in the nodule have been ruled out. A typical paramagnetic doublet persists even at very high temperature which has been proposed to be due to iron(III)phosphate. Formation of solid solution of Mn₂O₃–Fe₂O₃ has been observed in the heat treated nodule at 1073 K, which has been characterised by the Mössbauer technique.     

Iron-Iridium Mixed-Metal Carbonyl Clusters: A Mössbauer Study of the Structure and of the Adsorption of [Fe2Ir2(CO)12]2− on MgO

¹⁹³Ir and ⁵⁷Fe Mössbauer spectroscopy was used to investigate the structure of the [Fe₂Ir₂(CO)₁₂]^2- cluster compound and the adsorption of this cluster on hydrated MgO. Supported samples were prepared by impregnation of the magnesia with solutions of [Et₄N]₂[Fe₂Ir₂(CO)₁₂] in acetone. The Mössbauer and FT-IR spectra of the MgO-supported cluster confirm that the bimetallic carbonyl is molecularly physisorbed onto MgO without undergoing any transformation or decomposition. The easy solvent extraction of the intact cluster from the oxide surface excludes ion pairing between the cluster anion and the Mg²⁺ surface sites. Mössbauer spectra are in agreement with the refined structure of the molecular cluster and the temperature dependence of the ⁵⁷Fe Mössbauer spectra above 80 K is consistent with the low degree of interaction of the cluster with the support. This technique, therefore, appears to be promising in order to infer structural information when X-ray determination fails.     

Mössbauer and X-ray Investigation of Clay Minerals Originated from Libya

⁵⁷Fe transmission Mössbauer spectroscopy and X-ray diffractometry were used to study clay mineral samples originated from two different regions (Um-arrazm and Alkawasim) of Libya in order to get information about their mineralogical composition to assess their potential for use in the Libyan oil industry. In the samples originated from Um-arrazm calcite, akaganeite and nontronite while in the samples originated from Alkawasim quartz, akaganeite, montmorillonite, kaolinite, illite, mica and hematite were identified with different ratios by using diffraction method. The differences in the phase composition of iron-containing phases of samples from different localities have reflected in the complex Mössbauer spectra at both 300 K and 80 K. For the samples originated from Um-arrazm the Mössbauer parameters of subspectra were identified as nontronite and akaganeite.     

First observation of structural changes around the Tc in TlBaCaCuO4.5+y superconductor studied by57Fe Mössbauer spectroscopy

⁵⁷Fe Mössbauer spectroscopy was used to study⁵⁷Fe doped high T_c TlBaCaCuO_4.5+y superconductor between 70 and 295 K. Significant anomalous changes in the shape of the Mössbauer spectrum were observed around the T_c /105–120 K/. This experimental fact could be reproduced. Our finding can be associated with structural changes taking place around the T_c in TlBaCaCuO_4.5+y superconductor.