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A: Atomphysik
A 22: Heliumcluster (gemeinsam mit dem FV Molekülphysik)
A 22.3: Talk
Friday, April 7, 2000, 11:30–11:45, HS VII
Evidence for Superfluidity in OCS(pH2)15−17 Clusters inside 4He Droplets at 0.15 K — •S. Grebenev1,2, B. Sartakov3, A.F. Vilesov1,2, and J.P. Toennies2 — 1Ruhr-Universitat Bochum — 2Max-Planck-Institut fur Stromungsforschung — 3General Physics Institute, Moscow
Small clusters consisting of an OCS chromophore molecule surrounded by 14-17 para-H2 or ortho-D2 molecules within large pure 4He droplets and inside a mixed 4He/3He droplet have
been investigated by infra-red depletion spectroscopy. The rotational spectra of both isotopomers in the pure 4He droplets (T=0.38 K) exhibit a distinct Q-brunch, indicating the excitation of angular momentum around the OCS-symmetry axis. In the colder (T=0.15 K) 4He/3He mixed droplets the Q brunch remains in the OCS(oD2)15−17 spectrum but disappears in OCS(pH2)14−16. The corresponding decrease in moment of inertia in the pH2 clusters cannot be explained by the change in the Boltzmann factor and is attributed to a superfluid state.