Dear All I am trying to do a linear combination fit with Athena. To do that i want to first prepare my standard spectra. My unknown sample is (I presume) a combination of Cu and Cu(I)O (cuprite) and Cu(II)O (tenorite). I started with calibrating the Cu to 8979 eV as how the Athena manual say how to do it (I use the zero crossing point at the second derivative). This provided me an E0 and Eshift. I am doubting now for what I should do next: Cuprite and Tenorite have different oxidation states, meanin that the binding energies of the inner electrons will shift and in that way shifting the absorption edge of the compound. Should I look somewhere in a database (does that exist, or articles) for the absorption edge of cuprite and tenorite and set it like that or should I use the same E0 as i did for Cu? Another important thing for me, I have found some old data with some standard reference (powder spectra) measured in fluorescence mode, but my guess they are from different beamtimes, can I use data from different beamtimes/beamlines as standards in a linear combination fit? thank you in advance Pieter-Jan