[Ifeffit] [Question about XANES] Hello I'm a graduate student in Korea
bravel at bnl.gov
Fri Mar 17 10:31:54 CDT 2017
Doyoub's question is a common enough one that I added a section to the
Athena user manual:
My answer to Doyoub's question is much the same as Matt's.
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:
> 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.
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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
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