X-ray Absorption Spectral Analyses by Theoretical Calculations for TiO2 and Ni-Doped TiO2 Thin Films on Glass Plates

Abstract

Ni L-and Ti L-edge as well as Ti K-edge X-ray absorption experiments for TiO2 thin films and Ni-doped TiO2 thin films coated on glass plates were performed using synchrotron radiation to investigate the structures around Ni and Ti ions in the films. The obtained spectra were compared with the results of theoretical calculations. It has consequently been found that the spectral features were affected by a change in the oxidizing form of Ni ions due to hydrogen reduction, by the charge variation and/or slight orbital splitting of Ti ions, and by the magnitude of the interaction between the center Ti ion and neighboring Ti ions.

Weak Field Tuning of Transition-Metal Dopant Hybridization in Solid Hosts

“…The two peaks in L II edge correspond to the 3d states (t 2g , e g ) of Ni 2+ ion bonded to O 2− in O h symmetry. 57,61 A clear shift is observed in the L II edge t 2g /e g peak intensities as a function of the adsorbate dipole moment. This difference is attributed to the change in the Ni e g −O p hybridization with the ligands.…”

“…The Ni L III/II edge spectra (Figure a) for ligand-bonded TiO 2 :Ni films are split into L III and L II edges due to 2p spin–orbit coupling. The two peaks in L II edge correspond to the 3d states (t 2g , e g ) of Ni 2+ ion bonded to O 2– in O h symmetry. , A clear shift is observed in the L II edge t 2g /e g peak intensities as a function of the adsorbate dipole moment. This difference is attributed to the change in the Ni e g –O p hybridization with the ligands. , The well-resolved multiplet structure on the L III and L II edges of NH 2 -BZA-bonded films compared to that of NO 2 -BZA films suggests the ionic nature of the Ni bond, which is attributed to the weaker metal–oxygen orbital overlap.…”

Metal and Ligand K-Edge XAS of Organotitanium Complexes: Metal 4p and 3d Contributions to Pre-edge Intensity and Their Contributions to Bonding

“…By group theory, 3d−4p mixing may only occur in noncentrosymmetric environments, and hence the pre-edge features of centrosymmetric complexes are very weak. Systematic metal K-edge studies have also been applied to other first-row transition metals, including titanium. − However, previous Ti K-edge studies have focused primarily on Ti-oxides and relatively little is understood about the contribution of organometallic bonding to the Ti K-edge structure. , Hence, these studies will also be important in defining the nature of Ti−Cp bonding.…”

Metal and Ligand K-edge XAS of Titanium−TEMPO Complexes: Determination of Oxidation States and Insights into Ti−O Bond Homolysis

“…To obtain further insight into the electronic structure of these Ti−TEMPO complexes, we have initiated Ti and Cl K-edge X-ray absorption spectroscopic (XAS) studies on TiCl 3 TEMPO, TiCpCl 2 TEMPO, and TiCp 2 ClTEMPO (Cp = cyclopentadienyl) (Scheme ), as well as representative Ti(III) complexes TiCl 3 and Cp tt 2 TiCl (Cp tt = 1,3-di-tertbutylcyclopentadienyl). − Though there are examples of Ti(IV) XAS studies in the literature, − relatively few examples of Ti(III) XAS data are available , and to our knowledge, organometallic Ti(III) complexes have not been previously characterized by XAS. These studies develop a detailed understanding of the Ti 1s → 3d pre-edge transition and its sensitivity to changes in the oxidation state of the titanium.…”