Water vapor at a translational temperature of 1 K

We report the creation of a confined slow beam of heavy-water (D2 O) molecules with a translational temperature around 1 K. This is achieved by filtering slow D2 O from a thermal ensemble with inhomogeneous static electric fields exploiting the quadratic Stark shift of D2 O. All previous demonstrations of electric-field manipulation of cold dipolar molecules rely on a predominantly linear Stark shift. Further, on the basis of elementary molecular properties and our filtering technique we argue that our D2 O beam contains molecules in only a few rovibrational states.