Estudo da estrutura da superfície (001) de um monocristal de Cu90Au10 via difração de elétrons de baixa energia e difração de fotoelétrons

Abstract

In this work we have studied the atomic structure of Cu90Au10(001) surface by Low Energy Electron Diffraction (LEED) and Photoelectron Diffraction (PED). From the LEED analysis, we found two equally likely models for this surface, both forming a c(2 × 2) reconstruction, with gold atoms occupying substitutional sites in the first layer and with a second layer rich in copper. The proposed models differ by the types of defects introduced at first layer, one with 60 % of gold and the other with 20 % of holes at first layer replacing copper atoms. Our results also indicate a rumple in the first layer with gold atoms moving towards the vacuum and a relaxation of the second and third layer. The results obtained from the PED study also show a c(2×2) reconstruction with gold atoms occupying substitutional sites and a rumple in the first layer, but disagree from the LEED results, showing a higher concentration of copper in the first layer.