Search results for "SSB"
showing 10 items of 537 documents
Electric hyperfine interaction in199Hg fluorides
1985
With the current integration technique, the Mossbauer effect on the 158 keV, 5/2−→1/2− transition in199Hg was studied using the cubic HgF2 and the tetragonal Hg2F2 as absorbers; in the latter, a quadrupole splittingeQVzz=}- 9.0(2) mm/s was observed. Electron densities were calculated with the self-consistent-charge-extended-Hueckel-molecular-orbital method and δ〈r2〉=(3.26±0.11) fm2 derived. From the quadrupole splitting and the calculation, an effective antishielding factor almost twice that of the neutral Hg atom is derived.
Mössbauer effect study of the temperature and pressure dependence of the singlet-quintet intersystem crossing dynamics in an iron(II) spin crossover …
1988
The lineshapes of Mossbauer spectra of the iron(II) spin crossover complex [Fe(6-mepy)3 tren] (PF6)2 are affected by the dynamics of the HS⇌LS equilibrium. The lineshapes are reproduced with a stochastic two-state-relaxation-model yielding rate constants similar to those determined for related complexes in solution. Application of an external pressure of 150 MPa increases the relaxation rate.
The debye-waller factor in spincrossover molecular crystals: a mössbauer study on [FexZn1−x(ptz)6](BF4)2
1995
In a first approximation the Debye-Waller factor (DWF) of molecular crystals is factorized into a molecular and a lattice part:f=f m f l. In the case of spincrossover compounds there is the unique possibility to measure differences of both parts in the two spin states by switching the spin states with the LIESST effect. Measurements of the DWF depending on temperature, γ-ray direction and spin state were performed with57Fe-Mossbauer spectroscopy on three single crystals (R¯3) of the spincrossover system [FexZn1−x(ptz)6](BF4)2 (ptz=1-propyltetrazole), a concentrated sample withx=1 and diluted ones withx=0.30 andx=0.005. The DWF decreases from 10 to 300 K by a factor of ∼ 100 and its anisotro…
Rayleigh scattering of Mössbauer radiation on a myoglobin single crystal
1992
The RSMR technique was used to determine the fraction of radiation which is scattered elastically and inelastically, respectively, into Bragg reflections of a metmyoglobin single crystal. From this measurement 〈x2 1c〉=0.027±0.008 A2 has been determined which is due to long range correlated motions in analogy to acoustic and optic modes in solids.
On the metal distribution in the system GeTe−Sb2Te3
1988
The structures of GeSb2Te4, Ge2Sb2Te5 and GeSb4Te7 are not determined completely by means of classical X-ray or electron diffraction studies. We have measured the Mossbauer parameters of121Sb in these compounds as well as in their binary constituent Sb2Te3 as an attempt to improve our knowledge on the question.
A Mössbauer spectroscopic study of salt lake sediments from Qaidam basin
1992
Mossbauer spectroscopy, X-ray diffractometry and chemical fractionation have been used to study the clay smaples in sediments of Charhan playa and Qinghai lake. The spectral components of the Mossbauer spectra of the samples are attributed to Fe2+ ions in chlorite and siderite, Fe3+ ions in clay minerals and hematite, and partly in amorphous ferric hydroxides. The essential difference in the mineral composition of the sediments of both lakes is the presence of siderite in the samples of Char han playa, whereas it is absent in the samples of Qinghai lake. The fraction of the amorphous ferric hydroxides is higher in the sediments of Qinghai lake. Total Fe2+/Fe3+ ratios increase with sediment …
Surface Analysis in Archaeology Using the Miniaturized Mössbauer Spectrometer MIMOS II
2003
A miniaturized Mossbauer spectrometer (MIMOS II) which was designed and constructed for extraterrestrial applications, such as iron-containing rock and soil analysis on the planet Mars, has been employed to investigate the iron-containing constituents in the paintings of a Lekythos Greek vase. Greek pottery is commonly painted with black figures. The Mossbauer backscattering spectra recorded with MIMOS II at room temperature show that the hand-painted black figures contain hematite.
Optimization of a conversion electron Mössbauer spectroscopy gas flow He/CH4 proportional counter
1992
A new detector for CEMS has been built and optimized with respect to the statistical quality of spectra obtained. The optimization has been performed by measuring Mosbauer and pulse height spectra at in- and off-resonance. Single channel analyzer settings were calculated by a new optimization routine. A comparison of different detector designs has been performed using the statistical utility rate of spectra obtained from a stainless steel foil. A procedure for determining optimal operating parameters for ICEMS gas flow proportional counters is proposed.
Conversion electron Mössbauer study of vacuum and thermally treated vivianite
1990
Natural vivianite samples were studied by Mossbauer transmission and conversion electron spectroscopy. The intensities of ferrous doublets in vivianite and the widths of the resonance lines depend strongly on the origin of the samples, on their preparation history, and on exposures in vacuo as well as on thermal treatments. An additional ferrous doublet appearing in samples after vacuum treatment can be ascribed to a tetrahydrate phosphate phase appearing at the surface due to dehydration. Heating at 413 K in dry air for periods of 15–240 min causes a higher oxidation and decomposition rate at the surface region than in the bulk of vivianite. All results do not confirm the assumption publis…
Corrosion processes and their inhibition as studied by Mössbauer conversion and other electron spectroscopies
1989
To study corrosion processes of iron and steel and measures of their inhibition, a detailed knowledge of the phase composition and of phase transformations in very thin layers close to the attacked surface of the material is necessary. The information depths of integral (ICEMS) and depth selective (DCEMS) conversion electron Mossbauer spectroscopy are well suited for such investigations, but some effort is necessary if technical samples, i.e. nonenriched in57Fe, are to be studied. In many cases of practical importance, full information on the corroded surfaces cannot be got from Mossbauer spectra only, and a combination with Auger and photoelectron spectroscopies, in-including scanning and …