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 intercalated with cobaltocene by direct reaction of the organome-tallic compound in acetonitrile solutions. Powder X-ray and electron diffraction data 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 these misfit layer compounds, whereas the MX-TX(2) (M = Pb) interfaces are 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 phase, under UHV conditions, onto clean surfaces of binary and ternary chalcogenides, allowed the identification of these cobalt species as CoCp(2) and [CoCp(2)](+) (Cp = eta(5)-C5H5). It has also been shown by XPS that the intercalation of cobaltocene does not affect the core binding energies of the host matrix elements.