Resonant and core level photoemission spectroscopy of the misfit layer compound (SnS)1.20TiS2

(SnS)1.20TiS2 is member member of a family of misfit layer compounds with a general formula (MX)1+δTX2 in which M = Sn, Pb, Bi, Ln; T = Ti, V, Cr, Nb, Ta; X = S, Se and 0.08 < δ < 0.23. The triclinic compound (SnS)1.20TiS2 is built of double layers SnS and sandwiches TiS2 with Ti trigonally antiprismatic coordinated by S. These misfit layer compounds are synthesized at high temperature. The stability gained by the alternation of the stacking must therefore be considerable. The valence band spectrum, a constant initial state spectrum and core level spectra are presented here for (SnS)1.20TiS2 to discuss a possible charge transfer. A photoemission resonance is observed for the Ti 3d states at photon energies around 35 eV. The energy of the Ti 3p states is 35.4 eV below the Fermi level. The spectra presented here do not give any arguments for a charge transfer. Therefore we think that the stability of (SnS)1.20TiS2 does not arise from a charge transfer from one layer to another.