Cavity cooling of internal and external degrees of freedom of molecules

This paper reports on a proposal for cooling internal and external degrees of freedom of molecules. Cooling is achieved by suitably tailored Raman processes, where absorption of photons from a laser beams is followed by emission into the cavity resonances, thereby removing in average rovibrational and translational excitations, such that at the end of the process the internal degrees of freedom are cooled into the ground state and the external degrees of freedom are cooled to the cavity linewidth. The method relies on the enhancement of emission along certain resonances of a suitably designed resonator, while the laser, driving the molecules, is sequentially set to different frequencies in order to empty the higher excited ro-vibrational states of the molecules. The cooling efficiency is investigated numerically for the case of the OH radical, using ab-initio data and taking into account the rovibrational dependence of the Raman scattering into the cavity modes.