Dear Niken, I have had a look and i am afraid there are some problems, so what follows is not very positive. I am not sure your normalisation of the dilute samples is very good i ended up treating each spectrum slightly individually using a post-edge range of about 40-90 and adjusting the pre-edge range depending on the curviness of the pre-edge background. This is not ideal for linear combination fitting but i got spectra that looked like they had an edge step of 1. So That's fixable. But as you noticed the thiophene-10 and thiophene spectra are quite different. (you call it disulfide in your email but there are two thiophene and 1 disulfide spectra in the project. Ignoring self absorption which might give some relative peak intensity changes, i think this means they aren't the same thing Preparing your dilute samples some surface oxidation may have occurred in thiophene-10 there's a lump at 2481 or so that is bigger and displaced from the pure thiophene sample, this lump is quite reminiscent of some sulfate being present - this may be trace surface amounts, but the experiment will be sampling only about 10 microns worth of real sample so can be very important. This unfortunately is i think pretty unrecoverable. If the samples weren't well enough mixed and i mentioned earlier you are looking at only about 10 microns worth of powder in the post edge, then of course the sample you looked at is actually an unknown and not a standard, so a good fit in LCF might be the correct answer. Regards Fred BTW please use Dear Fred, dear professor fred just seems ridiculous to me. Prof. J F W Mosselmans Principal Beamline Scientist I18 Diamond Light Source Diamond House Harwell Campus Didcot Oxon OX11 ODE UK T 00 44 1235 778568 M 00 44 7785510211 E fred.mosselmans@diamond.ac.uk F 00 44 1235 778448 Never mind the W it's the tax that counts -- 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