Nanostructuring experiments in the system Ag(1Â 1Â 1)/Pb2+

The STM tip-induced deposition of Pb nanostructures at chemically polished Ag(1 1 1) electrodes covered with a Pb UPD coverage has been carried out in 0.01 M HClO4 containing 0.004 M Pb2+. Using a previously described tip- and field-induced nanostructuring method with a modified commercial STM instrumentation, the formation of Pb nanostructures is induced at low cathodic overvoltages by an anodic potential pulse modulation of the STM tip located at tunneling distances from the substrate surface. The technique has been performed with different pulse amplitudes and pulse duration of the tip modulation. The nanostructures formed by the application of pulses with amplitudes of +1 V are stable over extended time periods in the low cathodic overvoltage range, but are dissolved in the Pb underpotential deposition range, suggesting strongly that they consist of pure Pb deposits. Tip modulation amplitudes of +2 V result in the formation of nanostructures that remain stable also in the underpotential range of Pb deposition and are considered to contain also atoms originating from the Pt/Ir tunneling tip. The size and shape of the nanostructures varies with different tunneling tips, but is not noticeably affected by the duration of the pulse modulation. The presented results illustrate the possibility for the local tip-induced deposition of metal nanoclusters at foreign metal substrates in the low cathodic overpotential range of phase deposition.