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Abstract: Experimental and theoretical details concerning the directional elastic peak electron spectroscopy are presented. The application of this experimental method to the identification of a crystalline structure of surface layers is shown for Cu(111) and Ru(0001), which enables the analysis of different surface terminations associated with different sequences of atoms along the surface normal. Theoretical data are obtained by applying the multiple scattering theory and different sources of phase shifts. The quantitative analysis performed by an R-factor reveals almost the same populations of A and B terminated (0001) terraces and proves explicitly the presence of steps of atomic height on the clean Ru(0001) surface. This is not the case for the Cu(111) surface, where the terrace termination does not affect the distribution of atomic directions within the first few atomic layers. The averaging of theoretical data versus scattering volume defined by the sphere radius Rmax around the emitter site is discussed in view of the computation time optimization. [Copyright &y& Elsevier]

Abstract: The results of investigations of the adsorption system obtained by using directional elastic peak electron spectroscopy (DEPES), Auger electron spectroscopy and low energy electron diffraction are presented. The measurements were performed for the clean and Cu covered ruthenium surface at a coverage of 7 bilayers at room temperature. At early stages of growth the formation of two flat Cu bilayers was observed. Further adsorption leads to the nucleation of Cu(111) islands of the face centered cubic (fcc) structure. However, the experimental results reveal the formation of two fcc(111) domains which are mutually rotated by 180° arranged in the and orientations with respect to the substrate. Moreover, the quantitative analysis of DEPES data reveals nonequivalent (45%/33%) concentrations of these domains. [Copyright &y& Elsevier]

Abstract: The Ag/Au(111) adsorption system was investigated by Auger electron and directional elastic peak electron spectroscopies (DEPES). The change of the Auger peak heights for Au (NVV transition, 74eV) and Ag (MNN transition, 360eV) recorded during the continuous Ag deposition show the formation of the second layer before the completion of the first monolayer. Further evaporation leads to the nucleation of islands on the not-completed second layer. The intensity of elastically backscattered electrons was measured as a function of the incidence angle of the primary electron beam to obtain stereographic DEPES distributions at energies Ep=1.7keV and 2.0keV. About 8ML of Ag on Au(111) raises intensity contrast of the total map and of the particular peaks associated with crystallographic directions proving well ordered Ag(111) overlayer formation. The quantitative analysis of the contrasts for experimental and theoretical DEPES maps, the latter obtained by using the multiple scattering theory, suggests the coexistence of the reconstructed and nonreconstructed domains on the Au(111) surface. [Copyright &y& Elsevier]

Abstract: The intensity of elastically backscattered electrons at the primary electron beam energy 1.9keV was used to obtain a stereographic map of Au(111) by means of the directional elastic peak electron spectroscopy (DEPES). An experimental result is compared with the theoretical data obtained by using multiple scattering calculations (MS) performed for both not-reconstructed and model-reconstructed clusters. The lateral lattice misfit of the first layer leads to quantitative changes of theoretical intensities showing a sensitivity of DEPES to the short atomic chain axial order. This comparison proves that a main contribution of the experimental contrast originates from a higher background level. Moreover an anisotropy of the inelastic mean free path is discussed in the paper. [Copyright &y& Elsevier]