Observation of uniaxial structures of underpotentially deposited cadmium on Au(111) with in situ scanning tunneling microscopy

The atomic structures of several distinct adlayers of Cd underpotentially deposited onto a Au(111) surface in sulfuric acid electrolyte were revealed by in situ scanning tunneling microscopy (STM). Three ordered adlattices were observed, all of which have a long-range linear morphology rotated by 30 degrees from the substrate's lattice directions. Complete geometric descriptions and proposed structures are presented for each. A purely electrostatic model is insufficient to explain the banded morphology which is observed; therefore, other structure-forming interactions, including lattice strain, are discussed as possible contributors.