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UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS Guest
2024-11-24 23:03 |
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Conference: Bucharest University Faculty of Physics 2001 Meeting
Section: Atomic and Molecular Physics; Astrophysics
Title:
Mn2+ EPR Forbidden Transitions in Polycrystalline
and Amorphous Carbonates
Authors:
V. V. Grecu, D. Skliros
Affiliation:
Physics Faculty, University of Bucharest
E-mail
Keywords:
Abstract:
Hyperfine forbidden transitions in Mn2+ EPR spectra are known for a long time [1-5]. These transitions appear due to the mixing of different nuclear spin |m> states in an electronic spin |M> state. Thus in the electronic transition DM = ± 1 there are contributions, besides the usual Dm = 0, from nuclear states Dm = ±1, ±2 and so on. There are three approaches to calculate the intensities of these transitions, the perturbative approach [1], the Bir-Lupei procedure [2,3], and the intensity operator method [5]. In this paper a theoretical comparison of these 3 methods is performed. The analysis of Mn2+ EPR spectra in different polycrystalline and quasi-amorphous carbonates, spectra presenting strong hyperfine forbidden transitions, is presented. Advantages and limitations of the approximate methods are discussed with the emphasis on their use in the interpretation of disordered probes.
References:
[1] A.Abragam, B.Bleaney, Electron Paramagnetic Resonance of Transition Ions, Clarendon Press, Oxford, 1970.
[2] G.L.Bir, Sov.Phys.Solid State 5, 1628, 1964.
[3] V.Lupei, A.Lupei, I.Ursu, Phys.Rev.B 6, 4125, 1972.
[4] S.K. Misra, G.C.Upreti, Mag.Res.Review, Vol.12, 1-34, 1987.
[5] P.Mialhe, P.Quedec, Phys.Rev.B 14, 2757, 1976.
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