INITIAL-STAGE OF UNDERPOTENTIAL DEPOSITION OF PB ON RECONSTRUCTED AND UNRECONSTRUCTED AU(111)

We have studied the initial stage of Pb nucleation and growth on both reconstructed and unreconstructed Au(111) from 5.7mM Pb(NO3)2 + 50mM HClO4 using scanning tunneling microscopy. We have found that Pb clusters grow preferentially along the 23 x square-root 3 reconstruction of Au(111), a result that is similar to studies of metal deposition on reconstructed Au(111) in ultrahigh vacuum. A superperiodic structure of monolayer Pb was also observed and can be explained as a result of the rotation of the hexagonal-close packed Pb monolayer relative to the Au lattice. The coverage and average diameter of the growing Pb clusters were found to increase in two steps which correlate with the double peak in the voltammogram for underpotential deposition.