DIFFRACTION AND XPS STUDIES OF MISFIT LAYER CHALCOGENIDES INTERCALATED WITH COBALTOCENE

Polycrystalline samples of (PbS)(1.18)(TiS2)(2), (PbS)(1.14)(TaS2)(2), and (PbSe)(1.12)(NbSe2)(2), ternary chalcogenides, have been intercal ated with cobaltocene by direct reaction of the organome-tallic compou nd in acetonitrile solutions. Powder X-ray and electron diffraction da ta support a model in which the cobaltocene molecule is located in all TX(2)-TX(2) (T = transition metal; X = S2- or Se2-) interfaces of the se misfit layer compounds, whereas the MX-TX(2) (M = Pb) interfaces ar e empty. X-ray photoelectron spectroscopy (XPS) revealed the presence of two different oxidized cobalt species in these intercalated samples . Thus, in situ experiments of cobaltocene deposition from the gas pha se, under UHV conditions, onto clean surfaces of binary and ternary ch alcogenides, allowed the identification of these cobalt species as CoC p(2) and [CoCp(2)](+) (Cp = eta(5)-C5H5). It has also been shown by XP S that the intercalation of cobaltocene does not affect the core bindi ng energies of the host matrix elements.