Extended X-ray absorption fine structure investigation of the structure of iron 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 إ rapidly towards that of bulk iron (2.48 إ). The degree of order and coordination in the films also fall over this region. These changes are consistent with a loss of face-centred cubic structure. However, the structure does not exhibit a clear body-centred cubic SEXAFS fingerprint until around eight layers.