Fig. 7
From: Strongly bound excitons in anatase TiO2 single crystals and nanoparticles

Wavefunctions of the fundamental charge excitations in anatase TiO2. Isosurface representation of the electronic configuration when the hole of the considered excitonic pair is localised close to one oxygen atom. The coloured region represents the excitonic squared modulus wavefunction. a Bound exciton I at 3.76 eV. b Side-view of the bound exciton I at 3.76 eV. c Resonance II at 4.37 eV. d Bound exciton III at 4.28 eV