van der Waals forces between metal microclusters and fullerenes

Absolute integral cross sections for low-energy scattering of neutral sodium clusters ${\mathrm{Na}}_{\mathit{n}}$ (2<n<20) by ${\mathrm{C}}_{60}$ fullerenes have been measured. Cluster-cluster interaction is dominated by long-range van der Waals forces. Interaction constants determined from the data are in good agreement with the prediction of dispersion theory based on the spectral properties. The large cluster polarizabilities are responsible for the high strength of the interaction potential and, consequently, for the large center-of-mass cross sections (≳5000 A${\mathrm{̊}}^2$ for ${\mathrm{Na}}_{20\mathrm{-}}$ ${\mathrm{C}}_{60}$ collisions).