Photoemission studies of sulfur

Abstract

Photoemission measurements on polycrystalline orthorhombic sulfur films and glassy films of ${\mathrm{S}}_8$ molecules have been made at various photon energies up to 21.2 eV. There is essentially no difference in the densities of states of the polycrystalline and glassy films. The four peaks found agree in both amplitude and location with an adjusted semiempirical molecular-orbital calculation of the ${\mathrm{S}}_8$ molecule made by Chen. A deeper-lying broad peak which has been found in all the chalcogens at x-ray energies and attributed to $s$-like electrons is not observed at 21.2-eV photon energy; it is argued that further calculations are required to justify association of this deep x-ray peak with the $s$ electrons. The density of occupied states is completely different from that assumed by Cook and Spear to explain their optical data, but their ${\epsilon }_2\mathrm{}\left(E\right)\mathrm{}$ curve can also be reproduced moderately well by the present results.