Chemical shifts of silicon X-ray photoelectron spectra by polymerization structures of silicates

The binding energy of Si 2p electrons and the kinetic energy of the Si(KLL) X-ray-excited state were measured by using X-ray photoelectron spectroscopy (XPS) and X-ray Auger electron spectroscopy (XAES), respectively, for silicates with SiO₄ tetrahedra of various polymerization types. The resulting Si 2p XPS binding energies varied from 101.3 eV in merwinite (monomeric structure) to 103.4 eV in quartz and cristobalite (three-dimensional framework structure). A clear chemical-shift relation was observed, relating the polymerization structures of SiO₄ tetrahedra to the plots of their Si 2p XPS binding energy versus the kinetic energy of their Si(KLL) XAES spectra. Thus, the structural state of the surface silicates in various substances can be deduced from this chemical-shift relationship.