The electronic structure of SnS deduced from photoelectron spectra and band structure calculations.

SnS is a layer compound with a phase transition from a high-temperature β phase to a low-temperature α phase with a lower symmetry. Ab initio band-structure calculations are presented for both phases. The calculations show that the charge distributions in the two phases are very similar. However, the band gap is much larger in the α phase. The calculations are used to discuss the chemical bonding in the α and the β phase. Energy-dependent photoelectron spectra, using synchrotron radiation, and angle-resolved photoelectron spectra were obtained for α-SnS. The energy versus wave-vector curves deduced from the spectra are in good agreement with the band-structure calculations. Photoemission from the top of the valence band shows a resonance and an interference effect at photon energies of 25–30 eV.

A LEED and photoemission spectroscopy study of the surface of the incommensurate misfit layer and compound (SnS) 1.16 TaS2

The misfit layer compounds with stoichiometry (MX)1+δTX2 are composites of MX and TX2 layers, which are stacked alternatingly. This type of compound is known for M = Sn, Pb, Bi, La; T = Ti, Ta, Nb and X = S, Se. The MX layers adopt an SnS-type crystal structure. The compounds are synthesized at high temperature. Therefore the stability gained by the alternation of the stacking of the TX2 layers by MX layers must be considerable. LEED photographs and angular resolved UPS spectra are presented to show the large differences between the commensurate and the incommensurate directions in (SnS)1.16TaS2. Core level photoemission spectra indicate that there is no charge transfer from one layer to the other. Thus the stability of (SnS)1.16TaS2 cannot be explained by charge transfer