Surface extended X-ray absorption fine structure investigation of Fe islands grown on c(2 x 2) N/Cu(100) surface

We present the results of a surface extended X-lay absorption fine structur e (SEXAFS) investigation of the growth of Fe islands on the c(2 x 2) N/Cu(1 00) surface for different N doses. It is known from scanning tunnelling mic roscopy (STM) experiments that at subsaturation coverage adsorbed N atoms o n Cu(100) form square islands of c(2 x 2) periodicity and about 5 nm x 5 nm in size. These islands can self-organize in regular patterns. From the per sistence of the c(2 x 2) low energy electron diffraction patterns obtained for any Fe and N coverage we deduce (in agreement with previous STM results ) that Fe islands grow on surface areas which are not passivated by N atoms . In this study we estimate that we were able to produce Fe islands thicker than 10 atomic layers, a value higher than that observed using STM. The fi rst shell analysis of SEXAFS data shows that Fe atoms are arranged in an fe e lattice with tetragonal distortion, as observed in Fe/Cu(100) films, with the formation of bilayers and/or coalescence in small islands at the lowes t coverage studied (one monolayer). (C) 1999 Elsevier Science B.V. All righ ts reserved.