Home  About us  Contact
 

Mössbauer Data (mössbauer + data)

Distribution by Scientific Domains
Chemistry100%

Selected Abstracts

Manganoan rockbridgeite Fe4.32Mn0.62Zn0.06(PO4)3(OH)5: structure analysis and 57Fe Mössbauer spectroscopy

ACTA CRYSTALLOGRAPHICA SECTION C, Issue 3 2006
Günther J. Redhammer
The structure of the basic iron phosphate rockbridgeite [iron manganese zinc tris­(phosphate) penta­hydroxide] was reinvestigated with special emphasis on the cation distribution deduced from new X-ray and 57Fe Mössbauer data. Rockbridgeite is orthorhombic, space group Cmcm, and shows three different Fe sites, one with symmetry, another with m symmetry and the third in a general position. One phosphate group has the P atom on a site with m symmetry, while the other has the P atom at a site with mm symmetry. Two Fe sites are fully occupied by ferric iron, while Mn3+ and Fe2+ are situated at a third, principally Fe, site. Structural data, bond-valence sums and polyhedral distortion parameters suggest a new inter­pretation of the rockbridgeite 57Fe Mössbauer spectrum. [source]

Tin(II) Doped Anatase (TiO2) Nanoparticles: A Potential Route to "Greener" Yellow Pigments

CHEMISTRY - AN ASIAN JOURNAL, Issue 6 2009
Moumita Ghosh Dr.
Abstract Benign by design: Tin(II) doped anatase TiO2 nanoparticles, a potential candidate as environmentally benign yellow pigments, have been synthesized. The presence of Sn2+ in anatase structure has been confirmed by various analytical techniques including optical and 119Sn Mössbauer spectroscopy. During our exploration of compounds in the SnII -TiIV -O system, we discovered that hydrolysis of titanium alkoxide solution in the presence of SnII salts resulted in stable deep-yellow colored anatase nanoparticles. The samples were characterized by X-ray powder diffraction, electron microprobe, thermal analysis, transmission electron microscopy, and 119Sn Mössbauer spectroscopy. Mössbauer data of the yellow colored samples showed the presence of both SnII and SnIV in a distorted environment as expected in the anatase structure. It is suggested that the cationic charge imbalance is compensated by oxygen vacancies and/or hydroxyl groups as evidenced by Mössbauer data which show two types of SnII environments. When heated in air to 300,°C the samples changed color to completely white and 119Sn Mössbauer data of these samples showed only the presence of SnIV. These observations indicate that the origin of the yellow color in our Sn doped anatase nanoparticles arises from filled Sn 5s states just above the O 2p band, thus decreasing the band gap. The SnII doped anatase TiO2 nanoparticles reported here can potentially lead to environmentally benign yellow pigments. The simplistic nature of the synthetic procedure could easily be adapted to large-scale industrial manufacture. [source]

Low-Temperature EPR and Mössbauer Spectroscopy of Two Cytochromes with His,Met Axial Coordination Exhibiting HALS Signals,

CHEMPHYSCHEM, Issue 6 2006
Giorgio Zoppellaro Dr.
Abstract C-type cytochromes with histidine,methionine (His,Met) iron coordination play important roles in electron-transfer reactions and in enzymes. Low-temperature electron paramagnetic resonance (EPR) spectra of low-spin ferric cytochromes c can be divided into two groups, depending on the spread of g values: the normal rhombic ones with small g anisotropy and gmax below 3.2, and those featuring large g anisotropy with gmax between 3.3 and 3.8, also denoted as highly axial low spin (HALS) species. Herein we present the detailed magnetic properties of cytochrome c553 from Bacillus pasteurii (gmax 3.36) and cytochrome c552 from Nitrosomonas europaea (gmax 3.34) over the pH range 6.2 to 8.2. Besides being structurally very similar, cytochrome c553 shows the presence of a minor rhombic species at pH 6.2 (6,%), whereas cytochrome c552 has about 25,% rhombic species over pH 7.5. The detailed Mössbauer analysis of cytochrome c552 confirms the presence of these two low-spin ferric species (HALS and rhombic) together with an 8,% ferrous form with parameters comparable to the horse cytochrome c. Both EPR and Mössbauer data of axial cytochromes c with His,Met iron coordination are consistent with an electronic (dxy)2 (dxz)2 (dyz)1 ground state, which is typical for Type I model hemes. [source]