Papers by Author: B. Sepiol

Abstract: Grazing-Incidence Small Angle X-ray Scattering (GISAXS) and X-Ray Photon Correlation Spectroscopy (XPCS) studies of island growth in two different systems are presented: 5 ML of iron on MgO(001) and 10 ML of iron on Au(001). Due to a missing conducting surface Fe/MgO thinner than approximately 20 ML could not be studied previously by common methods like STM. Fe/Au(001) is interesting as atoms of gold diffuse easily through iron layers and form precipitates. The coarsening dynamics of these precipitates is investigated by XPCS in GISAXS geometry. Their growth depends on the crystallographic directions of the substrate and correlates with the morphology measured by STM microscopy. Measurements were performed at the ESRF in Grenoble.

Abstract: Nuclear resonant scattering (NRS) methods allow to determine diffusion coefficients and jump directions. The capability to measure the diffusion mechanism in ordered intermetallics on atomic scale by mean of NRS was shown in various experiments and in different geometries (transmission [1,2], Bragg [3], grazing incidence [4]). A combination of NRS and grazing incidence geometry can be used as a very sensitive tool to investigate thin films or near-surface-regions [4]. Fe3Si with a D03 structure stable at high temperature and with a well known diffusion mechanism was chosen for this investigation.