Fine structure of the Ca 2px-ray-absorption edge for bulk compounds, surfaces, and interfaces

Transformation mechanism of amorphous calcium carbonate into calcite in the sea urchin larval spicule

“…1 D and E, respectively. In calcite, the 2 main peaks (denoted 1 and 3, which are the Ca L 2 and L 3 peaks, respectively) are split, giving rise to 2 minor peaks [denoted as 2 and 4, the crystal field peaks (25)]. In synthetic ACC, peaks 2 and 4 are less intense and shifted closer to the main peaks, where they appear as shoulders.…”

Crystal-field splitting in coadsorbate systems:c(2×2)CO/K/Ni(100)

“…This inherently induces anisotropic field effects, with a CFS fine structure exhibiting angular dependence. 5 The two-dimensional ionic character of the present system is expected to induce particularly large spectral differences. A series of XAS spectra were thus recorded with the electric field vector ranging from parallel to the surface to 15°off the surface normal.…”

“…This approach is based on the premise that the interaction of the core hole with the excited electron dominates over the interaction with neighboring atoms, and has proven useful for a large number of systems. 4,5 Solid state effects are included as additional crystal-field terms that are added to the Hamiltonian. These are treated as free parameters and were allowed to vary to obtain the best fit to experiment.…”

Molecular and structural investigation of yukonite (synthetic & natural) and its relation to arseniosiderite

“…Hence it can provide specific information on the local character of the 3d 0 unoccupied states via the 2p 5 3d n excited electronic state (de Groot et al, 1990;de Groot, 2005). The Ca L 3,2 XANES spectra of octahedral coordination compounds with a positive crystal field have been described to consist of spin-orbit splitting which gives rise to two main peaks from the (a 2 ) 2p 3/2-e g , (b 2 ) 2p 1/2-e g final states along with a number of smaller peaks features (a 1 ) 2p 3/2-t 2g and (b 1 ) 2p 3/2-t 2g from transitions into the other empty states (de Groot et al, 1990;Himpsel et al, 1991;Borg et al, 1992;de Groot, 2005). The multi-peaks observed are due to the crystal field arising from the symmetry of the atoms surrounding the Ca 2+ ions leading to atomic and charge transfer multiplet effects.…”