Noble-Gas Nanoclusters with Fivefold Symmetry Stabilized in Superfluid Helium

Macroscopic samples (volume~cm³, atomic density~10¹⁹--10²⁰ cm^-3) of noble-gas nanoclusters (size~5--6 nm) were produced in superfluid helium by an impurity-helium gas injection technique. X-ray diffraction measurements show that the samples consist of weakly interacting nanoclusters with fivefold symmetry, such as icosahedra and decahedra. These results open new opportunities for fundamental research of nanoclusters of noble gases and other materials in well-controlled environments using experimental techniques requiring bulk samples.