Photoelectron spectroscopy of single-size Au clusters collected on a substrate.

We have successfully collected size-selected Au clusters from a liquid metal ion source on amorphous carbon substrates. The systematics of the photoemission spectra show that there was no significant fragmentation or coalescence of clusters with 7 or more atoms. We estimate the transition from metallic to local screening of the photoemission core hole to occur at a cluster size of approximately 150 atoms.