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Abstract  

The absolute values of the Debye-Waller factor for high-spin Fe/pyrrdtc/3 and low-spin Fe/pyroldtc/3 iron/III/ complexes /pyrrdtc-pyrrolidyl-N-carbodithioato, pyroldtc-pyrrole-N-carbodithioato/ were determined at room temperature. The obtained values of mean square displacement <x2> are in very good agreement with those determined by X-ray diffraction methods.

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Abstract  

Mössbauer spectra of low-spin ferric and high-spin ferrous compounds may be sensitive to the local humidity during the measuring process or to other parameters associated with the hydration degree of the sample. This effect is related to the location of water molecules around the t2g orbitals (dxy, dxz, dyz). The results indicate that for comparative studies all Mössbauer measurements must be carried out in well standardized conditions.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: M. Kumar Raju, P. Sugathan, T. Seshi Reddy, B. Thirumala Rao, S. Muralithar, R. Singh, R. Bhowmik, and P. Madhusudhana Rao

Abstract  

The high spin level structure of 73As nucleus is studied by populating the nucleus in 64Ni(12C,p2n)73As reaction. Level scheme is revised significantly. Positive parity sequence is extended up to 33/2+ and a negative parity side band is identified and extended up to high spins 37/2. In addition about 15 new energy levels and a total of about 25 new gamma transitions were placed in the level scheme.

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Abstract  

Neutron activation analysis has been applied to determine the purity of super-enriched176Yb as well as a diagnostic to optimize yields from the P.A.R.I.S. mass separator at Orsay. In 25 mass separations carried out during 3 months, 910 mg of super-enriched176Yb2O3 were recovered from the original 7 g of176Yb2O3 (97.5% enrichment). Neutron activation analysis has shown that only two per thousand of the initially present174Yb remained in the super-enriched product. Using this176Yb super-enriched (99.998%) target, micro-quantities of the high spin (16+) isomer178m2Hf were produced by the (,2n) reaction at the U-200 cyclotron in Dubna. Quantities of about 2·1012 atoms of this isomer have been irradiated by thermal neutron at the ORPHEE Reactor, Saclay. Only the neutron capture giving rise to the isomeric state 25/2 of179Hf has been measured, by detection -rays of this 25.1 days isomer. A cross section of 45±5 barns was obtained for178m2Hf(n,)179m2Hf.

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Abstract  

The57Fe Mössbauer spectra were measured in mixed crystals with different types of chemical bonding and crystal structure, i.e., (Fe,Al)(acac)3, (Fe,Co)(acac)3, K3[(Fe,Al)(ox)3]3H2O, and NH4(Fe,Al)(SO4)212H2O. The broadening of Mössbauer linewidth with increasing Fe3+–Fe3+ distance became less enhanced in the order: (Fe,Al)(acac)3>(Fe,Co)(acac)3, or K3[(Fe,Al)(ox)3]3H2O>(Fe,Al)(acac)3>NH4(Fe,Al)(SO4)212H2O. Furthermore, it was found that the broadening of the linewidth was larger in neat tris (-diketonato) iron(III) complexes than in (Fe,Al)(acac)3. Based on these results, the determining factors of the paramagnetic relaxation time other than Fe3+–Fe3+ distance and temperature were examined in terms of the Mössbauer linewidth as an indicator.

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study have room temperature μ eff values in the range 4.10–4.23 B.M. On decrease of temperature the μ eff values decrease to 2.08–2.13 at 40 K ( Fig. 3 ). For octahedral high-spin complexes of iron(II) with 5 T 2g ground term, the spin–orbit coupling

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measured at room temperature ( Table 3 ). The value of magnetic moment for manganese(II) complex is 6.1 μB corresponding to five unpaired electrons and octahedral coordination. The magnetic moment for Co(II) complex is 4.8 μB, suggesting an approximate high-spin

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Abstract  

Magnetic susceptibility and heat capacity due to spin-state excitations in LaCoO3 were analyzed with an irregular solution model composed of Co3+ ions in the low-spin ground state and in the high-spin excited state. An energy-levels diagram proposed by Ropka and Radvanskii [1] was used for the high-spin excited state. This analysis showed that the entropy of mixing is less than that of ideal solutions and the enthalpy of mixing is negative, indicating that the high-spin Co ions are arranged as far apart as possible.

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Abstract  

Oxo-centered trinuclear mixed-valence iron fumarate [Fe3O(O2CCH=CHCO2)3(H2O)3]·nH2O and iron malonate [Fe3O(O2CCH2CO2)3(H2O)3] have been prepared and studied by variable temperature Mössbauer spectroscopy. Iron fumarate complex showed a temperature dependent valence delocalization process. At 6 K two quadrupole split doublets corresponding to high-spin Fe(III) and high-spin Fe(II) state with an area ratio of 2:1 were observed and at 298 K there was only an averaged singlet peak. On the other hand malonate complex showed a localized valence state of high-spin Fe(III) and Fe(II) from low temperature to room temperature only with a slight variation in area ratio and spectral line broadening for Fe(II).

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Abstract  

Reaction products of [2]ferrocenophane with CF3COOH, CCl3COOH, CF3SO3H and SbCl5 were prepared. Mössbauer spectroscopic data and magnetic susceptibility measurements suggest the bond formation of Fe–H+ and Fe–Cl+, in which iron atoms are in a high-spin Fe/II/state.

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