Karrie Hanson

Surface science lettersAlloy formation in an electrodeposited monolayer

We find that a Au(111) electrode is substantially roughened after a single monolayer of Pb is electro-plated and stripped from the surface in a linear sweep experiment. The roughened electrode surface rearranges into 20 to 150 A diameter islands which are one atomic layer high, and separated by 20 to 50 A. This process is observed on all samples, for sweep rates ranging from 0.5 to 1000 mV/s. If a partial layer of Pb is plated and then stripped, pitting and an increased overpotential for Pb deposition are observed only in the areas adjacent to the plated sites. We suggest that these observations are consistent with the formation of a PbAu alloy in the surface layer.

Copper adlayer formation on Au(111) from sulfuric acid electrolyte

We have used in situ scanning tunneling microscopy to examine submonolayer Cu deposition from a sulfuric acid electrolyte on Au(111), sampling over large areas of the surface. We describe the growth of three distinct superlattice phases of Cu on the Au(111) surface before the onset of bulk deposition of Cu. In the earliest stages of deposition, during an electrochemical current peak, we observe the rapid growth of a low height phase, with an apparent height of 0.46±0.10 A. During this time, a second, monolayer‐height phase forms as small islands. We identify these phases as the (√3×√3)R30° and (1×1) Cu superlattices, respectively. A third phase appears at about 175 mV (versus Cu/Cu+2), and grows from nucleation points at the top edges of atomic steps and around the small (1×1) Cu islands. This phase, which we believe is a (5×5) Cu adlayer, slowly supplants the (√3×√3)R30° layer.

Alloy formation in an electrodeposited monolayer

Abstract We find that a Au(111) electrode is substantially roughened after a single monolayer of Pb is electro-plated and stripped from the surface in a linear sweep experiment. The roughened electrode surface rearranges into 20 to 150 A diamter islands which are one atomic layer high, and separated by 20 to 50 A. This process is observed on all samples, for sweep rates ranging from 0.5 to 1000 mV/s. If a partial layer of Pb is plated and then stripped, pitting and an increased overpotential for Pb deposition are observed only in the areas adjacent to the plated sites. We suggest that these observations are consistent with the formation of a PbAu alloy in the surface layer.