Elemental areal density calculation and oxygen speciation for flat glass surfaces using x-ray photoelectron spectroscopy

The elemental composition of multi-component glass surfaces is often insufficient for understanding the effects of surface treatments on properties. For this reason, a data analysis protocol has been developed to quantify the areal density of elements and to determine the oxygen speciation on glass surfaces by X-ray photoelectron spectroscopy (XPS) for flat glass surfaces on which other methods such as optical spectroscopy and thermal analysis cannot be applied due to their low surface area, surface contamination, insufficient signal, etc. Various oxygen species (hydroxyls, non-bridging oxygen, and bridging oxygen) are distinguished and quantified using a simple workflow involving the determination of accurate elemental relative sensitivity factors, adventitious hydrocarbon contamination correction, and the conversion of the corrected elemental glass composition to areal elemental density. The areal density of oxygen species is obtained by a standard glass model based stoichiometry approach and compared with a constrained peak fitting of the O 1s photoelectron spectrum. The data analytical protocol is first verified with a silica glass, and then applied to pristine re-melt surfaces and acid-leached surfaces of commercial multi-component silicate glasses. XPS analysis revealed that upon leaching, significant repolymerization of network oxygen is observed in the calcium aluminosilicate glass surface in contrast to the lack of restructuring in the soda-lime silica glass surface.