C 1s and Au 4f7/2 referenced XPS binding energy data obtained with different aluminium oxides, -hydroxides and -fluorides

A number of partially catalytically active aluminium compounds characterised by powder XRD have been investigated by XPS and XAES using a new method for static charge referencing 1, 2]. In detail, α-Al₂O₃, γ-Al₂O₃, boehmite γ-AlO(OH), bayerite α-Al(OH)₃, hydrargillite γ-Al(OH)₃, α-AlF₃, β-AlF₃, and AlF_2.3(OH)_0.7· H₂O and a hexa-fluoropropylene oxide (HFPO) modified γ-Al₂O₃ are examined. Well defined and chemically inert 20 nm gold particles are deposited as a nearly statistical distribution on the sample surface avoiding large coagulation effects. This procedure allows a determination of gold referenced XPS and XAES data sets. Binding energies (BE) of Al 2p, Al 2s, O 1s and F 1s photoelectron peaks as well as kinetic energies (KE) of Al KLL and F KLL Auger electron emission peaks are presented in relation to the Au 4f_7/2 BE reference. XPS and XAES data found in literature are, in most cases, C 1s referenced and scatter in a broad range. BE differences Δ between the C 1s charge reference BE and Au 4f_7/2 charge reference BE obtained with our samples are monitored by using the Al 2p orbital. These BE differences Δ clearly suggest that the chemical state of carbon observed in this study is not as uniform as required for reliable static charge referencing. Received: 24 June 1996 / Revised: 12 December 1996 / Accepted: 14 December 1996