Nitrogen doping of TiO2 photocatalyst forms a second eg state in the   Oxygen (1s) NEXAFS pre-edge
  Close inspection of the pre-edge in oxygen near-edge x-ray absorption fine structure spectra of single step, gas phase synthesized titanium oxynitride photocatalysts with 20 nm particle size reveals an additional eg resonance in the VB that went unnoticed in previous TiO2 anion doping studies. The relative spectral weight of this Ti(3d)-O(2p) hybridized state with respect to and located between the readily established t2g and eg resonances scales qualitatively with the photocatalytic decomposition power, suggesting that this extra resonance bears co-responsibility for the photocatalytic performance of titanium oxynitrides at visible light wavelengths. 
Artur Braun, Kranthi K. Akurati, Giuseppino Fortunato, Felix A.   Reifler, Axel Ritter, Ashley S. Harvey, Andri Vital, Thoma...
cond-mat.str-el cond-mat.mtrl-sci