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Wyświetlanie 1-3 z 3
Tytuł:
Investigations on the EPR Parameters of $KMgF_3$:$Cr^{+}$
Autorzy:
Kuang, M.
Wu, S.
Hu, X.
Li, G.
Zu, H.
Powiązania:
https://bibliotekanauki.pl/articles/1365348.pdf
Data publikacji:
2014-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.10.Dg
76.30.Fc
Opis:
The electron paramagnetic resonance parameters (i.e., g factor, hyperfine structure constant and superhyperfine parameters) of $KMgF_3$:$Cr^{+}$ are theoretically investigated from the perturbation formulae of these parameters for an octahedral $3 d^5$ cluster. As for the calculations of g factor and hyperfine structure constant, both the contributions from the crystal-field and charge transfer mechanisms are included based on the cluster approach. The metal to ligand charge transfer contribution to the g-shift Δg ( ≈ g-2.0023) is the same (negative) in sign and much larger in magnitude as compared to the crystal-field one. The conventional argument that the charge transfer contributions to zero-field splittings are negligible for $3 d^5$ ions in fluorides is no longer suitable for Δg analysis of $KMgF_3$:$Cr^{+}$ due to the dominant second-order charge transfer perturbation term. The charge transfer contribution to hyperfine structure constant exhibits the same sign and about 4% of the crystal-field one. The unpaired spin densities of the fluorine 2s, 2pσ and 2pπ orbitals are quantitatively acquired from the relationships with the relevant molecular orbital coefficients using the uniform model. The present treatments are superior to the previous calculations of directly fitting the experimental superhyperfine parameters.
Źródło:
Acta Physica Polonica A; 2014, 125, 5; 1224-1228
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Theoretical Studies of the Local Structures and EPR Spectra for $VO^{2+}$ in $MB_4O_7$ (M = Zn, Cd) Glasses
Autorzy:
Li, C.
Zheng, X.
Powiązania:
https://bibliotekanauki.pl/articles/1206562.pdf
Data publikacji:
2014-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.30.Fc
Opis:
Electron spin resonance spectral parameters (g factors $g_{∥}$, $g_{⊥}$ and hyperfine structure constants $A_{∥}$, $A_{⊥}$) of a tetragonal $V^{4+}$ centers in $MB_4O_7$ (M = Zn, Cd) are theoretically investigated by using the perturbation formulae for a $3 d^1$ ion in tetragonally compressed octahedra. In these formulae, the contributions to the g factors from the tetragonal distortion, characterized by the tetragonal field parameters $D_{s}$ and $D_{t}$ are taken into account by considering the local structures of the ligand octahedron around the $V^{4+}$ due to the Jahn-Teller effect. Based on the calculations, the ligand octahedra around $V^{4+}$ are suggested to suffer about 5.7% and 4.3% relative compression along $C_4$ axis for $MB_4O_7$ glasses with M = Zn and Cd, respectively, and negative signs of the hyperfine structure constants $A_{∥}$ and $A_{⊥}$ for $V^{4+}$ centers in $MB_4O_7$ glasses were suggested in the discussion.
Źródło:
Acta Physica Polonica A; 2014, 125, 1; 73-76
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Theoretical Studies of ESR Parameters and Local Lattice Structure of the Vanadate-Lithium-Borate Glasses
Autorzy:
Feng, W.
Zhao, M.
Li, T.
Zhang, X.
Xue, J.
Powiązania:
https://bibliotekanauki.pl/articles/1419845.pdf
Data publikacji:
2012-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.70.Ch
75.10.Dg
61.72.Bb
76.30.Fc
Opis:
Electron spin resonance spectral parameters of $V^{4+}$ ions in vanadate-lithium-borate glasses have been calculated by the crystal-field theory. The theoretical results are $g_{∥ }$ = 1.940, $g_{⊥}$ = 1.983 and $A_{∥ } = -175 \times 10^{-4} cm^{-1},$ $A_{⊥} = -65 \times 10^{-4} cm^{-1}$ which are good agreement with the experimental values ($g_{∥ }$ = 1.939(3), $g_{⊥}$ = 1.998(3) and $A_{∥ } = (170.6-176.4) \times 10^{-4} cm^{-1},$ $A_{⊥} = (61.3-71.4) \times 10^{-4} cm^{-1}$). In addition, the bond lengths of the local lattice structure are, respectively, $R_{∥ }$ = 1.5 Å and $R_{⊥}$ = 1.95 Å which have been shown to have a compressed tetrahedral geometry along the $C_4$ axis.
Źródło:
Acta Physica Polonica A; 2012, 122, 1; 167-169
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-3 z 3

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