X-Ray-Photoelectron-Spectroscopy Determination of the Valence Band Structure of Polymeric Sulfur Nitride,(SN)x

We report x-ray photoemission (XPS) measurements on polymeric sulfur nitride, ${\left(\mathrm{SN}\right)}_x$. Both valence-band states and core-level binding energies have been studied. The charge transfer $\delta$ in the ${\mathrm{S}}^{+\delta }{\mathrm{N}}^{-\delta }$ bond is estimated to be 0.30-0.42 electrons. The XPS spectra are compared with densities of states derived from a single-chain tight-binding calculation and also with three-dimensional orthogonal-plane-wave (OPW) calculations based on the two reported ${\left(\mathrm{SN}\right)}_x$ crystal structures. Good quantitative agreement is found with the OPW density of states.