Chlorine Adsorption on the Ag(110) Surface: STM and DFT Study

Adsorption of molecular chlorine onto the Ag(110) surface has been studied with low-temperature scanning tunneling microscopy, low-energy electron diffraction, and density functional theory calculations (DFT). At a coverage of 1/2 ML, chlorine forms a p(2 x 1) structure, which, with a further increase in coverage, transforms into a p(3 x 1) structure consisting of dimer rows. DFT modeling shows that both p(2 x 1) and p(3 x 1) phases can be explained by the adsorbate induced added-row reconstruction rather than formation of a simple overlayer. The p(2 x 1) phase consists of - Cl-Ag-Cl-Ag- rows, in which silver atoms occupy hollow sites. The p(3 x 1) structure contains a basement formed by a double Ag row and chlorine atoms decorating both of its edges. The increase of Cl coverage up to 0.78 ML leads to the formation of the quasi-hexagonal phase of chlorine atoms chemisorbed on the unreconstructed silver (110) surface. At further chlorine adsorption, the formation of stripes with an average period approximate to 25 angstrom aligned parallel to the ⟨001⟩ direction occurs as a result of the reconstruction, in agreement with DFT calculations.