X-ray photoelectron spectroscopic studies of sulfates and bisulfates interpreted by X alpha and band structure calculations

Valence-band and core-level x-ray photoelectron spectroscopy (XPS) studies of sulfate and bisulfate ions are reported. Sulfate and bisulfate ions cann ot be distinguished in their core XPS spectra, The valence band region show s a significant difference in the relative intensity and separation of two prominent peaks, and this difference can be used to distinguish between sul fate and bisulfate because the separation is larger in the case of sulfate (similar to 4 eV) than for bisulfates (similar to 3 eV), We show that this difference can be used in a wide range of sulfate and bisulfates, including main group and transition metal compounds: Li2SO4, Na2SO4, K2SO4, MgSO4, A l-2(SO4)(3), Fe-2(SO4)(3), FeSO4, Ni2SO4, Ag2SO4, (NH4)(2)SO4, NaHSO4, KHSO 4 and NH4HSO4 (some of these are hydrated). The sulfate and bisulfate spect ra can be interpreted by cluster (multiple scattered-wave X alpha calculati ons) and band structure calculations. A careful analysis of the valence ban d spectra of Li2SO4. H2O interpreted by band structure calculation results shows that the water of crystallization can be identified in the valence ba nd region. Copyright (C) 2000 John Wiley & Sons, Ltd.