Direct imaging of 13-Å-diam Au clusters using scanning tunneling microscopy

Controlled size clusters of Au with a diameter of 13 Å, prepared using a multiple expansion cluster source, have been supported on highly oriented pyrolytic graphite and observed with a scanning tunneling microscope. A reliable constant-current signature for a metallic cluster supported on a graphite substrate is identified. Images of the supported Au clusters are found to exhibit a narrow size distribution and a diameter which is in close agreement with the diameter predicted from conditions in the multiple expansion cluster source.