Properties of Cu films on Pt(1 1 1) revealed by AES, LEED, and DEPES

The experimental and theoretical results presented in this work concern the growth mechanism and structural investigations of the ultrathin copper layers on Pt(1 1 1) at the adsorption temperatures from 330 K to 450 K. The growth mode of Cu on Pt(1 1 1) and the crystalline structures up to the first four adsorbate monolayers (4 ML) were studied by using Auger electron spectroscopy, low-energy electron diffraction, and (in the case of 1 ML) directional elastic peak electron spectroscopy. At 330 K Cu forms a misfit adsorbate layer with a supercell of Cu(13 × 13) on Pt(12 × 12). The formation of the misfit Cu overlayer characterized by the LEED pattern continues to about 4 ML. At higher coverages the diffraction pattern characteristic of the Cu(1 1 1) surface was observed. At 450 K the pseudomorphic growth of 1 ML of adsorbate was noted. The experimental DEPES anisotropy maps compared with the theoretical data obtained by using the multiple scattering formalism confirms the misfit structure of the Cu layer at 330 K and pseudomorphic overlayer with threefold hollow adsorption sites of type A at 450 K.