[Ifeffit] [Question about XANES] Hello I'm a graduate student in Korea

[Bruce Ravel]

Doyoub's question is a common enough one that I added a section to the 
Athena user manual:

http://bruceravel.github.io/demeter/documents/Athena/bkg/short.html

My answer to Doyoub's question is much the same as Matt's.

B

On 03/17/2017 09:18 AM, Matt Newville wrote:
> Dear Doyoub,
>
>
>
> On Thu, Mar 16, 2017 at 10:59 PM, 김도엽(신소재공학과)
> <mdyk100 at postech.ac.kr <mailto:mdyk100 at postech.ac.kr>> wrote:
>
>     Hello
>
>
>
>     I'm a graduate student at POSTECH in Korea.
>
>     Currently, I obtained XANES spectra over a narrow energy range and
>     looked through the Athena manual
>
>
>     But, I'm kind of lost as to how exactly I'm supposed to normalize
>     raw data
>
>     which only has XANES spectra.
>
>
>     It would be very generous of you if you help me figure this out
>
>
> It's hard for us to answer questions that are so vague.
>
> Generally, it is recommended to collect XANES spectra out to at least
> 100 eV (and better 300 eV) above the edge in order to get a decent
> normalization.  Well, for "normal" hard X-ray spectra: for edges below
> about 3000 eV, you can often get by with less energy range.
>
> If you don't have that, it is sometimes OK to pick an energy as far
> above the edge as possible and pick an edge step so that all the spectra
> is 1.0 at that energy.  That is definitely prone to systematic biases in
> normalization.   Furthermore, if your data is particularly noisy, it can
> add a lot of variation in the normalization to use just a single energy.
>
> Which just brings me back to the original point: it's hard to say in
> general how to best handle XANES with a short energy range.
>
> --Matt
>
>
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-- 
  Bruce Ravel  ------------------------------------ bravel at bnl.gov

  National Institute of Standards and Technology
  Synchrotron Science Group at NSLS-II
  Building 743, Room 114
  Upton NY, 11973

  Homepage:    http://bruceravel.github.io/home/
  Software:    https://github.com/bruceravel
  Demeter:     http://bruceravel.github.io/demeter/