Orientation effects in soft X-ray magnetic circular dichroism

Autor: J. van Elp, B.G Searle
Rok vydání: 1997
Předmět:
Zdroj: Journal of Electron Spectroscopy and Related Phenomena. 86:93-106
ISSN: 0368-2048
DOI: 10.1016/s0368-2048(97)00051-0
Popis: The orientation dependence of magnetic circular dichroism (MCD) at soft X-ray absorption edges is discussed for paramagnetic 3d transition metal systems using ligand-field atomic multiplet calculations. Previous calculations have used a magnetic orientation along the z axis of the transition metal site. In the present work, three orientation directions are calculated: [001], [110] and [111]. Also an at-random spectrum is calculated which represents the actual situation for 3d transition metals in metalloproteins. The systems investigated can be divided into three classes based on the difference between the MCD effect for the different orientations. The first class contains spherical systems like, for instance, Fe 3+ (d 5 ) systems in O h and T d symmetries and Ni 2+ in O h symmetry. The differences between different orientations in these systems are small, or even absent. The second class contains first-class systems with a distorted local symmetry like Fe 3+ in D 2d symmetry and Ni 2+ in D 4h symmetry. The differences between the different orientations can be quite strong and result from differences in polarization for the left and right circularly polarized absorption spectra. The third-class systems exhibit relatively large zero-field splittings. The differences are very strong and are a result of the interaction between the zero-field splittings and the applied magnetic field. An example is Fe 2+ in D 2d symmetry.
Databáze: OpenAIRE
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