GLANCING ANGLE EXAFS OF ULTRA-THIN FILMS - NEGLIGIBLE ANOMALOUS-DISPERSION EFFECTS

Anomalous dispersion effects distort the EXAFS interference functions obtained at glancing angles of incidence. It is shown that the distort ions in the amplitude and phase shift are strongly dependent on the th ickness of the sample layer in a multilayer system. For thick films (s everal hundred A or more) our results are in good agreement with previ ous results in the literature. For ultrathin samples (several atomic l ayers thick) we show that the distortions become negligibly small. Our calculations are confirmed with experiment for a 8 monolayer bet Cu f ilm grown on a Ag(001) substrate.