2D Missing Row Structure of Cuprous Fluoride on Cu(001)

Cuprous fluoride (CuF), unstable in bulk, can be stabilized as a two-dimensional lattice. Controlled adsorption of fluorine on the copper surface is achieved by defluorination of a self-assembled submonolayer of C60F18 molecules. The detached fluorine atoms diffuse on the Cu(001) surface and form a stable (2√2 × √2)R45° superstructure revealed by scanning tunneling microscopy. X-ray photoelectron spectroscopy indicates a chemisorption state of F atoms and an absence of Cu(II) oxidation state of surface copper atoms. Modeling with density functional theory shows that the unit cell contains three fluorine atoms corresponding to a missing row structure. This study proves the existence of surface cuprous fluoride.