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Wyświetlanie 1-2 z 2
Tytuł:
Mössbauer Study of a Reduction Process in Iron Azaporphyrins
Autorzy:
Kaczmarzyk, T.
Jackowski, T.
Dziliński, K.
Kania, L.
Powiązania:
https://bibliotekanauki.pl/articles/1808101.pdf
Data publikacji:
2009-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
33.15.-e
Opis:
Electronic structure of the Fe(II)- and Fe(I)-complexes of mono- and diazaporphyrins studied by the Mössbauer spectroscopy is considered in this paper. It was found that in the presence of tetrahydrofuran molecules, the electron configuration of Fe(II) ions in the studied complexes corresponds to the intermediate spin state (S = 1) and the complexation of tetrahydrofuran solvent does not change this state. Interaction of tetrahydrofuran solvent with Fe(I)-azaporphyrins does not influence the electronic structure of Fe(I) ions coordinated to the porphyrin ligand, either. Electron configuration of Fe(I) ions in Fe(I)-octaethylporphyrins and Fe(I)-azaporphyrins is the same: ($d_{xy})^{2}(d_{xz},d_{yz})^{4}(d_{z}^2)^{1}$. The aza substitution is reflected in the values of the Mössbauer parameters. Increasing number of nitrogen atoms at meso positions causes the increase in the quadrupole splittings within the range 1.49-2.24 mm/s for the Fe(II) complexes and within the range 1.35-1.85 mm/s for the Fe(I)-porphyrins. Values of the isomer shifts are decreased from 0.51 to 41 mm/s for the same sequence of the Fe(II) complexes. For the Fe(I) reduced forms the isomer shifts are nearly constant and equal to about 0.37 mm/s. The Mössbauer results are discussed in association with EPR data for Fe(I)-porphyrins.
Źródło:
Acta Physica Polonica A; 2009, 115, 3; 656-659
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Influence of Reduction Process on the Iron-Molybdenum Nanoparticles in Modified MCM-41 Silica
Autorzy:
Surowiec, Z.
Wiertel, M.
Gac, W.
Budzyński, M.
Powiązania:
https://bibliotekanauki.pl/articles/1381974.pdf
Data publikacji:
2014-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.80.+y
78.67.Bf
78.67.Rb
75.20.-g
Opis:
Iron-molybdenum silica mesoporous materials were obtained by the application of direct hydrothermal method. The influence of high temperature samples reduction in the $H_2$ flow on their structural and magnetic properties was studied. Four samples with different metal contents relative to silica were investigated. The study was carried out by means of X-ray diffraction, $\text{}^{57}Fe$ Mössbauer spectroscopy and the temperature programmed reduction method. With an increasing metals content, primary pores of MCM-41 transformed into the bottle-like pores, and then into the slit-like ones. Reduction and heat treatment caused the α-Fe, $Fe_2Mo$, and Fe-Mo alloy formation. Iron and molybdenum atoms after being released into the silica matrix, where they were embedded, create clusters or crystallites. It was observed that the high temperature reduction caused partial transformation of highly dispersed Fe-Mo oxides species initially embedded in silica walls into crystallites big enough to give magnetic sextet component in the Mössbauer spectra.
Źródło:
Acta Physica Polonica A; 2014, 125, 3; 846-849
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-2 z 2

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