On Wednesday 05 May 2010 11:24:16 am Andrew Campos wrote:
Thanks so much for the link and the advice! I appreciate it greatly. I will advise my lab mates as such and may have to only use the fluorescence data if that is indeed the case.
I also included the file where the lower temperature is included and you might come to the same conclusion. The samples that I ran were pre-sieved, and the ones included in the .prj file aren't so that should be pursued prior to running the experiment. If they crush the particle and sieve the sample, I think that we can be more certain that this is not the case. This was very helpful!
I would actually come to a different conclusion about your low tempertaure data. Those data look like they suffer from self-absorption (or over-absorption, if you prefer). See http://xafs.org/Experiment/OverAbsorption That is, the sample measured in the low T mesaurement appears to be too concentrated for the fluorescence measurement, however the transmission data in that case looks just fine. As Anatoly said, you could correct the fluorescence data after the fact. Given that you have the corresponding transmission data, this correction can be done accurately by comparison. I am not clear why the low and high temperature data behave differently, but then I am not clear quite what is being measured in each case. As for the high temperature data -- it is hard to stress highly enough the importance of good sample preparation. B -- Bruce Ravel ------------------------------------ bravel@bnl.gov National Institute of Standards and Technology Synchrotron Methods Group at NSLS --- Beamlines U7A, X24A, X23A2 Building 535A Upton NY, 11973 My homepage: http://xafs.org/BruceRavel EXAFS software: http://cars9.uchicago.edu/~ravel/software/exafs/