Towards direct laser cooling of barium monofluoride

Cold molecular gases are the starting point for many novel and interdisciplinary applications ranging from few- and many-body physics to cold chemistry and precision measurements. However, while there has recently been significant progress in the direct cooling of molecules, the preparation of a new molecular species in the cold temperature regime still requires a careful optimization of the available cooling techniques. We have performed vibrational spectroscopy of monofluoride (BaF), to determine the cooling and repumping transitions of this molecule with an accuracy of better than 100 MHz. Together with a detailed modeling of the cooling processes, this brings laser cooling of this species within reach.