<p>This thesis addresses the electronic structure of vanadium and copper oxides using soft X-ray absorption (SXA) spectroscopy and resonant inelastic X-ray scattering (RIXS) at high brightness synchrotron radiation sources. In RIXS incident photons, tuned to the energy of specific absorption resonances, are inelastically scattered leaving behind a low energy valence excitation in the system studied. Effects of electron localization are reflected by the occurrence of low-energy excitations in form of dd- and charge-transfer excitations that are modelled by cluster calculations. Band-like states are dominating when the intermediate core excited state is delocalized.</p><p>RIXS at V 2p and O 1s resonances has been used to study the electronic structure of the monovalent vanadium oxides VO<sub>2</sub> and V<sub>2</sub>O<sub>3</sub>, and of the mixed valence compounds, NaV<sub>2</sub>O<sub>5</sub> and V<sub>6</sub>O<sub>13</sub>. For NaV<sub>2</sub>O<sub>5</sub> and V<sub>6</sub>O<sub>13</sub> significant contributions from localized low-energy excitations reflect the partly localized character of their valence band electronic structure, whereas VO<sub>2</sub> and V<sub>2</sub>O<sub>3</sub> appear mostly as band-like. Effects of carrier doping are addressed for the case of Mo doping into VO<sub>2</sub> and reveal a quasi-rigid band behavior. In the cases of VO<sub>2</sub> and V<sub>6</sub>O<sub>13</sub> the temperature dependent metal-insulator transition could be monitored by following the spectral evolution of bands originating from V 3d and V 3d - O2p hybridized states. For Na<sub>2</sub>V<sub>3</sub>O<sub>7</sub> nanotubes it was possible to selectively probe states from the apical and the basal oxygen sites of VO<sub>5</sub> pyramids that constitute these nanotubes. Furthermore, the RIXS technique has been demonstrated to be highly valuable in characterizing the charge transfer processes that accompany lithium insertion into vanadium oxide battery cathodes. Finally, for insulating cuprates RIXS at O 1s, Cu 3p and Cu 3s resonances has been recorded at high-resolution for the detailed investigation of crystal field excitations.</p>
| Identifer | oai:union.ndltd.org:UPSALLA/oai:DiVA.org:uu-4290 |
| Date | January 2004 |
| Creators | Schmitt, Thorsten |
| Publisher | Uppsala University, Atomic and molecular physics, Uppsala : Acta Universitatis Upsaliensis |
| Source Sets | DiVA Archive at Upsalla University |
| Language | English |
| Detected Language | English |
| Type | Doctoral thesis, comprehensive summary, text |
| Relation | Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, 1104-232X ; 987 |
Page generated in 0.0021 seconds