The effect of XPS background removing method on the appraisal of Ti and Fe: the case of phlogopites and brookite

The determination of the oxidation state and structural role of transition metals in minerals, especially when carried out on single crystal, is nowadays a crucial challenge. XPS spectrum of these elements have the 2p core level region usually rich of features but the choice of the method for the background removing can seriously affect the gained information and the results of the quantitative analysis. Here, single crystal of brookite (TiO2) and SA and BHG natural micas (the structure of the last two has previously studied by [ Ventruti et al. (2009) Eur. J. of Min., 21, 385-396.and Schingaro et al. (2005) Clays and Clay Min., 53(2), 179-189.) are investigated to examine the effect of background subtraction on Ti2p and Fe2p signals. The backgrounds used are (i) the “Linear” background, (ii) the traditional “Shirley” background, (iii) three different Tougaard-like backgrounds and (iv) the more recent “Shape parameter, ” method [ Salvi et al. (2004) SIA, 36, 1402-1412]