title: Persistent molecular superfluid response in doped para-hydrogen clusters.
abstract: Direct observation of superfluid response in para-hydrogen (p-H(2)) remains a challenge because of the need for a probe that would not induce localization and a resultant reduction in superfluid fraction. Earlier work [H. Li, R. J. Le Roy, P.-N. Roy, and A. R. W. McKellar, Phys. Rev. Lett. 105, 133401 (2010)] has shown that carbon dioxide can probe the effective inertia of p-H(2) although larger clusters show a lower superfluid response due to localization. It is shown here that the lighter carbon monoxide probe molecule allows one to measure the effective inertia of p-H(2) clusters while maintaining a maximum superfluid response with respect to dopant rotation. Microwave spectroscopy and a theoretical analysis based on Feynman path-integral simulations are used to support this conclusion.
authors.affiliation: Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada.
authors.forename: P L
authors.initials: PL
authors.lastname: Raston
authors.forename: W
authors.initials: W
authors.lastname: Jäger
authors.forename: H
authors.initials: H
authors.lastname: Li
authors.forename: R J
authors.initials: RJ
authors.lastname: Le Roy
authors.forename: P-N
authors.initials: PN
authors.lastname: Roy