Dear Neil, Sorry this may be too exact an interpretation of your English, but if you are looking at the exafs then calibration is normally pretty irrelevant as long as it is not wildly out, as you refine E0 anyway in the fitting. The bond distances will be very little altered by this. If you are looking at XANES and it is 3/4 then CeL3 as I am sure you know has two "white lines" for four and one for three and the ratio of the two peaks can be used to Look at oxidation state mixtures, I think you should be able to align the peaks and fit the area e.g. Burnham AD, Berry AJ, 2014, The effect of oxygen fugacity, melt composition, temperature and pressure on the oxidation state of cerium in silicate melts, Chemical Geology, Vol:366, ISSN:0009-2541, Pages:52-60 Best wishes Fred -- This e-mail and any attachments may contain confidential, copyright and or privileged material, and are for the use of the intended addressee only. If you are not the intended addressee or an authorised recipient of the addressee please notify us of receipt by returning the e-mail and do not use, copy, retain, distribute or disclose the information in or attached to the e-mail. Any opinions expressed within this e-mail are those of the individual and not necessarily of Diamond Light Source Ltd. Diamond Light Source Ltd. cannot guarantee that this e-mail or any attachments are free from viruses and we cannot accept liability for any damage which you may sustain as a result of software viruses which may be transmitted in or with the message. Diamond Light Source Limited (company no. 4375679). Registered in England and Wales with its registered office at Diamond House, Harwell Science and Innovation Campus, Didcot, Oxfordshire, OX11 0DE, United Kingdom