REVERSIBLE COVERAGE-DEPENDENT CU + CLADS-]CUCL TRANSITION ON CU(111)/CL2 SURFACE

The early stages of halogenide film formation during the halogenation of solids were studied on Cu(111)/Cl2 as a model system by AES and TDS. The main result of this work is the direct observation of the transition from the chemisorbed state (Cl(ads)) to the halogenide state (CuCl) during Cl2 adsorption and vice versa during diffusion or desorption of CuCl. It was found that apart from the way of formation of chlorine coverage (adsorption of Cl2 or transformation from two-dimensional CuCl film to three-dimensional CuCl islands or CuCl sublimation) the state of each local region of the surface was defined by only the amount of coverage: the chemisorbed state corresponds to one atom adsorbate layer but the halogenide state to two or more atom adsorbate layers.