Characterization of the (X)over-tilde1A1, and (A)over-tilde1B2 electronic states of titanium dioxide, TiO2

The strong band system at 536 nm, tentatively assigned as the (A) over tilde B-1(2) <- (X) over tilde (1)A(1)(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) over tilde (1)A and (A) over tilde B-1(2) state, respectively. The bond angle, theta, and length, R-TiO2, for the (A) over tilde B-1(2) state were determined to be 100.1 and 1.704 angstrom. The dispersed fluorescence was analyzed to determine the nu(2) bending frequency. omega(2)(a(1)), 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.