A Surface Extended X-ray Absorption Fine Structure investigation of Fe islands grown on c(2x2) N/Cu(100) surface

We present the results of a surface extended X-ray absorption fine structure (SEXAFS) investigation of the growthof Fe islands on the c(2×2) N/Cu(100) surface for different N doses. It is known from scanning tunnelling microscopy(STM) experiments that at subsaturation coverage adsorbed N atoms on Cu(100) form square islands of c(2×2)periodicity and about 5 nm×5 nm in size. These islands can self-organize in regular patterns. From the persistence ofthe c(2×2) low energy electron diffraction patterns obtained for any Fe and N coverage we deduce (in agreementwith previous STM results) that Fe islands grow on surface areas which are not passivated by N atoms. In this studywe estimate that we were able to produce Fe islands thicker than 10 atomic layers, a value higher than that observedusing STM. The first shell analysis of SEXAFS data shows that Fe atoms are arranged in an fcc lattice with tetragonaldistortion, as observed in Fe/Cu(100) films, with the formation of bilayers and/or coalescence in small islands at thelowest coverage studied (one monolayer).