Re: [Ifeffit] too small bond length in R space

Dear all： Thanks a lot for Sebastiano and Patridge's advise. I tried all your advises.I did avoid the white line before,but I find when I avoid the first scattering peak after white line,the first peak of R space disappeared.Because usually the first scatering peak is related to the first coordiantion shell,can I think the first peak in R space less 1A is a real peak instead of noise？ And I am still confuse about how to distinguish whether a peak near 1A(without phase correction)is a real peak or noise.If I think the background,spline,rbkg have been choosed ok,Can I think the remaining low diatance peak is real? Thanks Sincerely, zhanfei ihep of China

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发件人: "Patridge, Christopher" 发送时间: 2014年11月9日 星期日 收件人: "XAFS Analysis using Ifeffit" 抄送: 主题: Re: [Ifeffit] too small bond length in R space

That is a difficult problem. You might consider using the structural model as a guide for setting the background r max by comparing the data and model if you are confident that the model is close to the sample you are studying. Good luck.

Chris Patridge

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On Nov 9, 2014, at 6:54 AM, ZHAN Fei wrote:

Dear all： I encounter a problem of exafs fit in an example of Mo which have Mo-O Mo-S Mo-Mo bond.The problem is that the Mo-O peak in R space has too small bond length (less than 1.4A(+0.5A for phase correction) ).Because when 1.2>rbkg>0.68 there is little change in spectrum of R and k space,and when I increase the value of rmin of forward Fourier transform the peak changes little,so I think it's not a noise.But when I try to fit it use the 1.35A path of Mo-O,I can't fit it well. Could you give me some advise about fit too small bond length,or recommend papers of similar situation? picture of R space is attached. Thanks Sincerely, zhanfei ihep of China <R space.png>

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