supersonic nozzle has been shown to successfully produce ultracold bare metal clusters of
even the most refractory of metals, tungsten and molybdenum. Clusters of up to 25 atoms
may be readily prepared using this technique. Mass‐selective resonant two‐photon
ionization spectra of Mo2 produced in this fashion show that the dimer is efficiently cooled in
the expansion T trans< 6 K, T rot∼ 5 K, and T vib∼ 325 K. We have rotationally resolved the …