Neutron Scattering Studies of superfluid helium confined in preplated nanoporous materials.

One dimensional systems have been of long standing interest due to a profound difference from their 2 and 3 dimensional counterparts whose properties can be described in terms of quasi-particles. This quasi-particle picture breaks down completely in one dimension where the fundamental excitations are collective and described by the universal Tomonaga-Luttinger liquid (TLL) theory. Superfluid helium confined in one-dimensional templated materials, such as MCM-41, provide an attractive model system for studying the properties of a TLL. Unfortunately, the pore size attainable in these materials is too large to reach the one-dimensional limit. Preplating these porous materials with an adsorbate offers a route to smaller pore sizes where one-dimensional confinement can occur. We will present the results of neutron scattering studies of the excitations of superfluid helium confined in MCM-41 preplated with a monolayer of Argon. The observed scattering departs dramatically from the bulk superfluid and may be consistent with a TLL.