X-ray and ultraviolet photoemission of polymeric sulfur nitride (SN)x

Abstract

We have determined, both experimentally and theoretically, the one-electron density of states surrounding the Fermi level in polymeric sulfur nitride, (SN)x. The experimental measurements were performed using X-ray and ultraviolet photoemission spectroscopy (XPS and UPS), while the theoretical studies employed calculations based on OPW and pseudopotential band structures of (SN)x. The XPS measurements included observations of N and S core level shifts which yielded values for the number of charged-transferred electrons of about 0.4. This is compared with our recent XPS data on a related compound, Se4N4, yielding a charge transfer of 0.3 e only. One of the major observations from both XPS and UPS was that of low photoemissive yields near the Fermi level. Our calculations of the photoemissive response tensor, Dμν (E,hν), show that this low yield near EF is primarily a result of dipole matrix element energy dependence.