Characterization of the X ¹A₁ and à ¹B₂ electronic states of titanium dioxide, TiO₂

The strong band system at 536 nm, tentatively assigned as the à ¹B₂← X ¹A₁(000-000) vibronic transition, in TiO₂ has been recorded at a spectral resolution of 40 MHz, both field free and in the presence of a static electric field. The Stark induced shifts were analyzed to determine the permanent electric dipole moments of 6.33 ± 0.07 D and 2.55± 0.08 D for the X ¹A₁ and à ¹B₂ state, respectively. The bond angle, θ, and length, R_Ti-O, for the à ¹B₂ state were determined to be 100.1° and 1.704 Å. The dispersed fluorescence was analyzed to determine the ν₂ bending frequency, ω₂ (a₁), of 322 ± 6 cm^-1. A molecular orbital model is used to rationalize the change in bonding upon excitation and the results compared with electronic structure predictions.