Atomic impact experiments with free helium-3 and helium-4 clusters

J. Gspann, R. Ries

Robert E. Zillich, Markku Leino, Alexandra Viel

R. Guardiola, Jesús Navarro

Nicholas L S Martin, B N Kim, C.M. Weaver +1 more

Synopsis Experiments and theory will be presented for the emission/absorption of 1.17 eV photons by electrons during the electron-impact excitation of a helium target in a laser field.

Slava Grebenev, Jan Peter Toennies, Andrei F. Vilesov

The infrared spectrum of single oxygen carbon sulfide (OCS) molecules was measured inside large superfluid pure helium-4 droplets and nonsuperfluid pure helium-3 droplets, both consisting of about 10(4) atoms. In the helium-4 droplets, sharp rotational lines were observed, whereas in helium-3 only a broad peak was found. This difference is interpreted as evidence that the narrow rotational lines, which imply free rotations, are a microscopic manifestation of superfluidity. Upon addition of 60 helium-4 atoms to the pure helium-3 droplets, the same sharp rotational lines were found; it appears that 60 is the minimum number needed for superfluidity.

Arend Niehaus, P. van der Straten, G.R. Woestenenk