A low energy pathway to CuCl2 at Cu(110) surfaces

Abstract

The reaction of hydrogen chloride gas with partially oxidised Cu(110) surfaces follows a different structural pathway than its reaction with a clean surface. In the latter case a c(2 × 2)Cl structure develops which is compressed in the [110] direction for chlorine atom concentrations greater than 5.5 × 10¹⁴ cm⁻². In contrast, the presence of oxygen leads to the formation of linear “Cl-chains” orientated in the [100] direction which closely resemble those of bulk CuCl₂. These Cu(II) like structures are unstable at room temperature decomposing to form c(2 × 2)Cl. Using XPS and STM we have investigated the formation of the CuCl₂ like surface species and propose that it derives from the unusual reactivity of transient copper adatoms released from the p(2 × 1)O by the exothermic formation of water.