Nanomanipulation of ligand-stabilized Au-55 clusters by means of scanning tunneling microscopy

We have investigated ligand-stabilized Au-55 clusters by means of scanning tunneling microscopy (STM) at room temperature on highly oriented pyrolytic graphite (HOPG) and other substrates. Single clusters or groups of several clusters were transferred between sample and STM tip using conventional vo ltage pulses. With a new variant of voltage pulses called "field-emission p ulses", cluster shells were partly destroyed by heating with the field-emis sion current, resulting in a "hardening" of the cluster layer. HOPG substra te surfaces with most of the clusters removed exhibit "pearl chains" of clu sters attached to step edges.