Abstract

One important prerequisite for high-precision spectroscopic measurements on cold molecules is the ability to control the translational as well as internal degrees of freedom of the molecules. For neutral molecules ultracold translational temperatures and recently also transfer to the internal ground state with up to 80% efficiency have been achieved [1]. For molecular ions of a variety of species, the motion can be cooled efficiently via sympathetic cooling by laser cooled atomic ions down to temperatures in the milli Kelvin range [2]. Cooling of the internal degrees of freedom has so far not been possible in non-cryogenic environments since the sympathetic cooling does not affect the internal degrees of freedom and the black-body radiation will distribute the molecular population over several ro-vibrational states [3]. Here, we present an experiment which constitutes to the best of our knowledge the first demonstration of an all-optical internal state cooling scheme for molecular ions.

© 2009 IEEE