INVESTIGATION OF THE B<sup>3</sup>Σ<sup>+</sup>, V=0 STATE IN ALUMINIUM MONOFLUORIDE

The aluminium monofluoride (AlF) molecule is a promising candidate for laser cooling and trapping experiments a .Here, we describe experiments studying the hyperfine structure of the b 3 Σ + , v = 0 state b .We first determined its radiative lifetime in a pulsed excitation -delayed ionization scheme and measured the rotational structure using (1+2)-REMPI.We recorded laser-induced fluorescence spectra of the b 3 Σ + , v = 0 ← X 1 Σ + , v = 1 transition of AlF molecules from a bright buffer gas source.The fluorescence detection works background-free because visible photons are emitted after UV excitation.From the obtained line positions, we determined the relevant fine-and hyperfine structure parameters.In a next step, laser-induced fluorescence spectra were recorded after excitation on the b 3 Σ + , v = 0 ← a 3 Π Ω , v = 0 transition; we use all three spin-orbit (Ω = 0, 1, 2) manifolds of the a 3 Π state.These spectra were used to improve the uncertainty of our previous measurement of the spin-orbit coupling parameters in the a 3 Π, v = 0 state by almost two orders of magnitude.We observed the b 3 Σ + , v = 0 → X 1 Σ + , v bands, which are result of the spin-orbit coupling of the b 3 Σ + , v = 0 state with the nearby A 1 Π state.