X1Σ+ and a3Σ+ states of LiCs studied by Fourier-transform spectroscopy

We present the first high-resolution spectroscopic study of LiCs. LiCs is formed in a heat-pipe oven and studied via laser-induced fluorescence Fourier-transform spectroscopy. By exciting molecules through the X (1)Sigma(+)-B (1)Pi and X (1)Sigma(+)-D (1)Pi transitions vibrational levels of the X (1)Sigma(+) ground state have been observed up to 3 cm(-1) below the dissociation limit enabling an accurate construction of the potential. Furthermore, rovibrational levels in the a (3)Sigma(+) triplet ground state have been observed via singlet-triplet mixing in the higher excited states. With the help of coupled channels calculations, accurate singlet and triplet ground-state potentials were derived reaching the atomic ground-state asymptote. These potentials yield an accurate determination of the singlet and triplet ground-state dissociation energies and allow first predictions of cold collision properties of Li+Cs pairs.