Properties of Pt on Cu(111) revealed by AES, LEED, and DEPES

Abstract

The investigations of Pt on Cu(111) were carried out to reveal the growth mode and crystalline structure of the adsorbate with the use of Auger electron spectroscopy (AES), low energy electron diffraction (LEED), and directional elastic peak electron spectroscopy (DEPES). Auger signal recorded during the continuous Pt adsorption on Cu(111) at 330 K confirms the layer by layer growth mode. LEED patterns observed at 1ML of Pt show the formation of the compressed adlayer. At higher coverages such as 3ML and 6ML the increase of the lattice constant of the topmost Pt layer, which approaches the bulk value of Pt(111), is noted. DEPES investigations performed for 1ML of platinum indicate the nucleation of adsorbate domains characterized by A/CBA and B/CBA stacking sequences at the Pt/Cu interface, which at higher coverages lead to the nucleation of mutually rotated by 180° Pt islands. Experimental DEPES data were compared to theoretical results obtained with the use of the multiple scattering (MS) calculations for different adsorption geometries including the Pt and Cu intermixing at the interface. The quantitative analysis of the data made by R-factor calculations enabled the determination of Pt domain populations already at 1 ML and 6 ML.