title: Molecular superfluid: nonclassical rotations in doped para-hydrogen clusters.
abstract: Clusters of para-hydrogen (pH₂) have been predicted to exhibit superfluid behavior, but direct observation of this phenomenon has been elusive. Combining experiments and theoretical simulations, we have determined the size evolution of the superfluid response of pH₂ clusters doped with carbon dioxide (CO₂). Reduction of the effective inertia is observed when the dopant is surrounded by the pH₂ solvent. This marks the onset of molecular superfluidity in pH₂. The fractional occupation of solvation rings around CO₂ correlates with enhanced superfluid response for certain cluster sizes.
authors.affiliation: Department of Chemistry, University of Waterloo, Waterloo, Ontario, N2L 3G1, Canada.
authors.forename: Hui
authors.initials: H
authors.lastname: Li
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Le Roy
authors.forename: Pierre-Nicholas
authors.initials: PN
authors.lastname: Roy
authors.forename: A R W
authors.initials: AR
authors.lastname: McKellar