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SIMPLE EXPLANATION OF THE EXPERIMENTAL 57Fe MӦSSBAUER ISOMER SHIFT OF IRON COMPOUNDSтезисы доклада
- Авторы: Dedushenko S.K., Perfiliev Yu D.
- Сборник: LXXII International conference "NUCLEUS-2022: Fundamental problems and applications" (Book of Abstracts)
- Тезисы
- Год издания: 2022
- Место издания: Amirit Saratov
- Первая страница: 304
- Последняя страница: 305
- Аннотация: According to the existing concept, a Mӧssbauer isomer shift (IS) is proportional to the electron density at an iron-57 nucleus (ρ0): IS (R14.42-Rg2)ρ0, where R14.4 and Rg are the radii of the iron-57 nucleus in the excited and ground states, respectively. Judging by the estimates obtained in [1], the radius of the iron nucleus in the ground state is larger than that in the excited one. Hence, an increase in ρ0 must lead to a decrease in IS. Frequently, e.g. in iron oxocompounds, the rise of oxidation state (escape of electrons from valence shell) leads to the decrease of IS. This is usually explained by the shielding effects. We suggest applying the approach of the valence shell hybridization to explain the regularities of the IS change [2]. It is easy to show that to electrons on 4s-orbital create the electron density at the iron nucleus, which is equivalent to the density created by the full set of fully filled 4s4pn3dm-hybridized orbitals: |ψ_s (0)|^2=∑_(i=1)^(1+n+m)▒|_(sp^n ⅆ^m)^((i) ) (0)|^2 , where n = 0…3 and m = 0…5 are the numbers of the 4p and 3d-orbitals involved in the hybridization. Using this property, we can suggest that the directional chemical bonds, which iron cation establishes with surrounding anions, influence on the IS; this influence being independent on the number of the bonds. Assuming that the IS is proportional to the average bond length, we can explain the observed experimental dependencies. At the same time, d and p-electrons do not create a density on the nucleus but affect the interatomic distances. Moreover, we concluded that the electron shell of each anion of the iron polyhedron can make noticeable additional contribution to the electron density at the iron nucleus. This makes it possible to explain the dependence of the IS on the iron coordination number. 1. L.L. Walker, et al., Phys. Rev. Let. 6, 98 (1961). 2. S.K. Dedushenko and Yu.D. Perfiliev, Hyp. Int. 243, 15 (2022).
- Добавил в систему: Перфильев Юрий Дмитриевич