The B1Π and D1Π states of LiCs studied by Fourier-transform spectroscopy

We report on a high resolution study of two excited electronic states of the LiCs molecule, namely the B(1)Pi and the D(1)Pi. The experimental data are derived from the Fourier transform spectroscopy on the ground states X(1)Sigma(+) and a(3)Sigma(+) [Phys. Rev. A 75, 042513 (2007)]. Along with the laser induced fluorescence also collisionally induced satellites are observed, which expand the data sets for the B(1)Pi and D(1)Pi states. The lower state, B(1)Pi, is found to be free of significant local perturbations, although a strong dependence of the Lambda-doubling on the vibrational and the rotational quantum numbers indicates a noticeable influence of the nearby (1)Sigma(+) states. A set of Dunham coefficients and a potential energy curve for this state are derived. In contrast, the energy levels of both the e and f parities of the D(1)Pi state were found to be strongly perturbed, making a precise description within a single channel model impossible. Nevertheless we present an approximated experimental potential energy curve which can be applied in a further deperturbation analysis. We discuss the prospects of these electronic states for the formation of cold LiCs molecules in a magneto-optical trap of mixed species.