High resolution spectroscopy with molecular beams and tunable lasers

High resolution Doppler-free laser techniques are used in beam experiments to improve the spectroscopic description of complex diatomic molecules. The case of TiO is considered here for its implication in reaction dynamics st udies and its interest in Astrophysics. Two absorption bands in the visible have been analyzed: B(3)Pi - X-3 Delta (1 - 0) and c(1) Phi - a(1) Delta ( 0 - 0). Owing to accurate wavenumber measurements, it has been possible to extend the analysis to high rotational quantum numbers and to carry out det ailed spectroscopic calculations. They show that a careful revisiting of th e TiO electronic structure is necessary.