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Experimental and Theoretical Studies of Fine Structure in Polarized Ni K X‐Ray Absorption Spectra of NiO Single Crystals
Author(s) -
Vedrinskii R.V.,
Kraizman V.L.,
Novakovich A.A.,
Elyafi Sh.M.,
Bocharov S.,
Kirchner Th.,
Dräger G.
Publication year - 2001
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/1521-3951(200107)226:1<203::aid-pssb203>3.0.co;2-d
Subject(s) - xanes , quadrupole , spectral line , scattering , chemistry , condensed matter physics , exciton , antiferromagnetism , atomic physics , electronic band structure , single crystal , absorption edge , non blocking i/o , absorption spectroscopy , molecular physics , crystallography , physics , band gap , optics , biochemistry , astronomy , catalysis
Polarized Ni K XANES of single crystal NiO is studied experimentally and theoretically for two crystal orientations relative to the polarization and wave vectors of incident X‐ray beam. The spectra calculated by the full multiple scattering method for a spin‐dependent cluster potential and incomplete screening of the core hole appear to be in an excellent agreement with the experiment. The low energy pre‐edge peak is shown to be caused by the quadrupole transitions of the Ni 1s electron to an exciton‐type state shifted down by ∼4 eV from the empty e g high‐energy conduction band under the influence of the core hole potential. The feature caused by the Ni 1s → e g band dipole transitions is also recognized in the spectrum. It is shown that the same mechanisms, which are responsible for the formation of the pre‐edge fine structure in the oxides of early 3d‐metals in 3d 0 state, work in the considered case as well. A comparative analysis outlining the significance of different mechanisms for the pre‐edge structure formation in cases of early and late 3d‐metal spectra is presented. The antiferromagnetic order of the absorber is taken into account within one‐electron approximation.