Grazing incidence X-ray diffraction of lead monolayers at a silver (111) and gold (111) electrode/electrolyte interface

Using grazing incidence geometry and a thin-layer cell, X-ray scattering has been used to study the structure of electrochemically deposited monolayers of lead on silver (111) and gold (111) electrodes in situ. When deposited on silver, the lead orders in a hexagonal close-packed (hep) geometry with the lead lattice compressed 1.2% relative to bulk lead. A rotational epitaxy angle of 4.4° was observed. From the width of the first-order diffraction peak, the domain size was determined to be > 150 Å, indicating that even immersed in solution, the lead forms a well-ordered two-dimensional solid. On a gold (111) substrate, the lead monolayer was again found to order into a hcp geometry, incommensurate with the gold. The lead layer was compressed 0.7% relative to bulk lead, with a domain size >100 Å. © 1988 American Chemical Society.