Dispersed laser-induced fluorescence of molecular ions. Identification of new low-lying electronic states of TiCl+ and TiF+

The dispersed laser-induced fluorescence technique has been applied for the first time to metallic molecular ions. The TiCl+ and TiF+ ions were produc ed by a high-voltage discharge in helium with traces of TiCl4 or TiF4. A c. w. dye-laser and a grating plate spectrometer were used to record low-resol ution spectra of these species in the visible. This leads to the observatio n of new low-lying electronic states of these ions: the C(3)Pi (similar to 1535 cm(-1)) state of TiCl+, the B(3)Delta (similar to 2040 cm(-1)) and C(3 )Pi (similar to 2200 cm(-1)) states of TiF+. The identification of these ne w states contributes to a better characterisation of the first 3000 cm(-1) of the energy level diagrams of these molecules. The experimental position of the C(3)Pi: state of TiCl+ is in good agreement with theoretical predict ions given by a Ligand Field Theory model [C. Focsa, M. Bencheikh, L.G.M. P ettersson, J. Phys. B: At. Mel. Opt. Phys. 31 (1998) 2857]. We have extende d these calculations to the TiF+ isovalent ion, taking advantage of the new experimental data. Both experimental and theoretical new results presented in this paper are expected to help future investigations on these species. (C) 1999 Elsevier Science B.V. All rights reserved.