Detection of multiple species through isosbestic points in UV-photoemission spectra: Application to sulfide adsorption on copper

Abstract

When the spectra corresponding to successively greater adsorbate coverages are superimposed, there is often a singular point through which they all pass. This is recognized as an isosbestic point, which is shown should be present whenever there is only a single adsorbate overlying the substrate. The lack of such a point consequently indicates the existence of multiple adsorbate species. These criteria are applied to the adsorption of O₂, H₂S and benzenethiol on Cu(410). For H₂S, two species are detected and assigned to surface and incorporated sulfur.