Hi Eugenio, Perform your analysis on the data, using different values for k-max. If you are successfully extracting structural information which is different from the standard, you will find fitted parameters which: --are stable with changes in k-max --take on values that are different from those for the standard, taking into account the error bars (i.e. the values for the standard do not fall within the error bars for the sample for at least one parameter) --are stable with changes in k-weight. --Scott Calvin Sarah Lawrence College On Aug 21, 2009, at 11:35 AM, Eugenio Otal wrote:

Hi, thanks for the help. Let me be more clear. I am trying to know the limits to use information from the second shell, from XRD I found that the phase is present, but I want to know if I can use the signal to obtain more information about second neighbors. I have this sample and some more where I find a second shell signal, the doubt is about how far can I trust in this information, is there a limit in k-space to believe in the information of the second shell and try to fit it? I attach the R-space graph with the same limits for the FT, there are still differences, what should I check to be sure the information I can get from the second shell is trustable and not a problem of the noisy signal? Thanks, euG

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