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

Abstract

Abstract : 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. For the lead monolayer deposited on sliver, the lead was found to order in a hexagonoal closed packed (hcp) geometry with the lead lattice compresssed 1.2% relative to bulk lead. A rotational epitaxy angle of 4.4 deg was observed. From the width of the first order diffraction peak, the domain size of the lead was determined to be 300 A indicating that even when deposited from a 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 layer, incommensurate with the gold. The lead was compressed 0.7% relative to bulk lead, with a domain size 200 A. Keywords: X-ray electrode; Lead(Metal); Gold electrode; Interface structure; Electrodeposition.