Dynamical behavior of x-ray absorption and scattering at the L edge of titanium compounds: experiment and theory

Detailed experimental results and model caclulations for the evolution of the x-ray fluorescence in the vicinity of the {ital L} absorption edge of titanium in metallic Ti and TiO and insulating TiO{sub 2} and BaTiO{sub 3} are presented. Behavior characteristic of x-ray Raman scattering was found in all samples. We develop a model that describes the valence band emission below the L{sub 3} absorption threshold in terms of the calculated partial density of states and the Kramers-Heisenberg x-ray scattering formalism. Linear muffin-tin orbital band structure calculations were used for the projected density of states in the model. In the region below the L{sub 3} absorption edge very good agreement between experiment and the model was found for all compounds. We propose a mechanism for the energy shift of the emission spectra for TiO{sub 2} and BaTiO{sub 3}. An explanation of the Raman energy loss in terms of the excitation of a valence electron into localized states of {ital d} symmetry in the conduction band is also provided. {copyright} {ital 1999} {ital The American Physical Society}