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

The strong band system at 536 nm, tentatively assigned as the A~ 1B2 X~ 1A1(000-000) vibronic transition, in TiO2 has been recorded at a spectral resoln. of 40 MHz, both field free and in the presence of a static elec. field. The Stark induced shifts were analyzed to det. the permanent elec. dipole moments of 6.33 0.07 D and 2.55 0.08 D for the X~ 1A1 and A~ 1B2 state, resp. The bond angle, .theta., and length, RTi-O, for the A~ 1B2 state were detd. to be 100.1 and 1.704 .ANG.. The dispersed fluorescence was analyzed to det. the .nu.2 bending frequency, .omega.2 (a1), of 322 6 cm-1. A MO model is used to rationalize the change in bonding upon excitation and the results compared with electronic structure predictions.