CoO layers have been grown by exposing to oxygen the (001) body-centered-tetragonal (bct) surface of a Co ultrathin film epitaxially grown on Fe(001). Different oxide thicknesses in the 2–15 ML range have been investigated by means of synchrotron-radiation-based techniques. X-ray photoelectron spectroscopy has been used to check the formation of the oxide films; X ray photoelectron diffraction has given information concerning the symmetry of their unit cell; grazing incidence X-ray diffraction has allowed to evaluate precisely their in-plane lattice constant. The films show a CoO(001) rocksalt structure, rotated by 45° with respect to the bct Co substrate, with the [100] direction parallel to the substrate [110] direction. Their in-plane lattice constant increases as a function of thickness, to release the in-plane strain due to the 3% mismatch between the bulk CoO phase and the underlying substrate.
ABSTRACTWe describe the two dimensional structure of n-Alkyl Thiols, CH3(CH217SH(C18, self-assembled on the surfaces of Au(111) and Ag(111). By using Grazing Incidence X-ray Diffraction (GIXD), we show that C18 forms ordered and dense monolayers. Although the properties of Au and Ag are very similar (for instance, the lattice constants of Au an Ag are nearly identical), the structure of C18on these two substrates is very different.
ABSTRACTA microstructural study on surfactant templated silica films is performed by
coupling traditional X-Ray Diffraction (XRD) and Transmission Electronic
Microscopy (TEM) to Grazing Incidence Small Angle X-Ray Scattering (GISAXS).
By this method it is shown that spin-coating of silicate solutions with
cationic surfactant cetyltrimethylammonium bromide (CTAB) as a templating
agent provides 3D hexagonal structure (space group P63/mmc) that
is no longer compatible with the often described hexagonal arrangement of
tubular micelles but rather with an hexagonal arrangement of spherical
micelles. The extent of the hexagonal ordering and the texture can be
optimized in films by varying the composition of the solution.