[Ifeffit] too small bond length in R space

[ZHAN Fei]

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


> -----原始邮件-----

> 发件人: "Patridge, Christopher" <patridgc at dyc.edu>
> 发送时间: 2014年11月9日 星期日
> 收件人: "XAFS Analysis using Ifeffit" <ifeffit at millenia.cars.aps.anl.gov>
> 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 
> 
> > On Nov 9, 2014, at 6:54 AM, ZHAN Fei <zhanfei at ihep.ac.cn> 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>
> > 
> > 
> > 
> > 
> > 
> > 
> > 
> > _______________________________________________
> > Ifeffit mailing list
> > Ifeffit at millenia.cars.aps.anl.gov
> > http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit
> 
> _______________________________________________
> Ifeffit mailing list
> Ifeffit at millenia.cars.aps.anl.gov
> http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit