FINE-STRUCTURE OF THE CA 2P X-RAY-ABSORPTION EDGE FOR BULK COMPOUNDS, SURFACES, AND INTERFACES
1991 (English)In: Physical Review B Condensed Matter, ISSN 0163-1829, E-ISSN 1095-3795, Vol. 43, no 9, 6899-6907 p.Article in journal (Refereed) Published
The fine structure of the Ca 2p soft-x-ray-absorption edge is studied for a variety of bulk compounds (Ca metal, CaSi2, CaO, and CaF2), for surfaces and interfaces [CaF2(111), BaF2 on CaF2(111), Ca and CaF2 on Si(111)], and for defects (F centers in CaF2). The observed multiplet structure is explained by atomic calculations in a crystal field [cubic O(h) for the bulk and threefold C3-nu for the (111) surfaces and interfaces]. While the bulk spectra are isotropic, the surface and interface spectra exhibit a pronounced polarization dependence, which is borne out by the calculations. This effect can be used to become surface and/or interface selective via polarization-modulation experiments, even for buried interfaces. A change in valence from Ca2+ to Ca1+ causes a downwards energy shift and extra multiplet lines according to the calculation. The energy shift is observed for F centers at the CaF2 surface and for the CaF2/Si(111) interface.
Place, publisher, year, edition, pages
1991. Vol. 43, no 9, 6899-6907 p.
IdentifiersURN: urn:nbn:se:kth:diva-84172DOI: 10.1103/PhysRevB.43.6899ISI: A1991FD38900006OAI: oai:DiVA.org:kth-84172DiVA: diva2:499236
NR 201408052012-02-132012-02-132012-02-13Bibliographically approved