Extended X-ray absorption fine structure investigation of the structure ofiron overlayers on Cu(111)

Surface extended X-ray absorption fine structure (SEXAFS) has been used to probe the structure of ultrathin films of iron on Cu(111), With increasing film thickness, the interatomic separation falls from 2.57 Angstrom rapidly towards that of bulk iron (2.48 Angstrom). The degree of order and coordin ation in the films also fall over this region. These changes are consistent with a loss of face-centred cubic structure. However, the structure does n ot exhibit a clear body-centred cubic SEXAFS fingerprint until around eight layers. (C) 2000 Elsevier Science B.V. All rights reserved.