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

Abstract

The strong band system at 536 nm, tentatively assigned as the Ã ¹B₂←  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  ¹A₁ and Ã ¹B₂ state, respectively. The bond angle, θ, and length, R_Ti–O, for the Ã 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.