CU-FE AND FE-CU INTERFACES INVESTIGATED BY SYNCHROTRON RADIATION-INDUCED PHOTOEMISSION

The formation of an interface between copper and iron has been studied by valence band (VB) photoemission spectroscopy induced by synchrotron radiation. VB analysis revealed the presence of a weak interaction occurring between these two metals. Copper growth on the iron substrate causes the Cu3d peak maximum to shift 0.5 eV towards the high binding energy side, compared with the value obtained for bulk copper. Smaller changes on the iron VB are observed upon Fe growth on the copper substrate and the Fe3d peak maximum is at 0.7 eV below the Fermi level from low coverage onward; this energy value is the same as that observed for pure iron. A layer-by-layer growth mode for these two metals is suggested and overlayer interdiffusion with the substrates has been ruled out.