[Ifeffit] Difficulty with normalization of XAS spectra

[Robert Gordon]

Two things:

1. This is a volunteer community. Asking us to download a massive file 
and parse through it to find a data file is not a reasonable request. 
Pick an example and attach it as a txt file (energy, mu(E) or E, I0, IF 
). In fact, since the graph looks like the data were grossly 
over-sampled for XANES, you might want to sieve it to a more reasonable 
step size such as 0.1 to 0.3 eV through the edge. That will also help 
with file size.

2. If the graph you attached is representative of the data, the data 
were not collected over a large enough energy range for normalisation. 
Next time, try +/- 100 - 200 eV below and above the edge (maybe 250 above).

-R.

On 2024-04-10 5:22 a.m., jesse walters wrote:
> Hi all, I have some spectra collected by a collaborator, Francesco 
> Ressico, a PhD student at Uni Bologna,  (see attached .h5 file below) 
> and we are having trouble normalizing the Fe K edge spectra. The data 
> are for serpentine group minerals
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> Hi all,
>
> I have some spectra collected by a collaborator, Francesco Ressico, a 
> PhD student at Uni Bologna,  (see attached .h5 file below) and we are 
> having trouble normalizing the Fe K edge spectra. The data are for 
> serpentine group minerals and were collected in fluorescence mode. In 
> the attached file, the correct X array value is 'energy_enc', the data 
> type is 'xas', and the y array should be 'mu_fluo_det0'. The spectra 
> are already normalized for the incoming beam energy (although this can 
> also be done using 'flou_det0/i0'). There are multiple spectra in the 
> file, any one of them can be chosen to test the procedure.
>
> After loading the spectra, I am able to plot the raw spectra correctly 
> (see attached). But when I try to normalize the pre and post edge 
> regions and plot the normalized spectra, the software only gives a 
> blank plot. I have tried changing the normalization type, polynomial 
> type, range, etc for both the pre and post edge, but nothing seems to 
> work. I also tested different spectra, but with similar results.
>
> Does anyone have suggestions for how these data can be normalized?
>
> The h5 file is too large, so here is a dropbox link 
> https://urldefense.us/v3/__https://www.dropbox.com/scl/fi/d8k5s67vli0mq97ac520y/COR21_79_Xastransect_79_F1_THC.h5?rlkey=33ragg4p6x9rx65t9yvi5kewe&dl=0__;!!G_uCfscf7eWS!Y2vfGwfONNMo1aLgkAnnXaF5bQ8shgtgTi51NUeYhIeIHAvFmLRm9we3b2lAA2ZANf1WrgLChlCGWCg0N--jlHp3IM5xIQjzyaIPkA4$  
> <https://urldefense.us/v3/__https://www.dropbox.com/scl/fi/d8k5s67vli0mq97ac520y/COR21_79_Xastransect_79_F1_THC.h5?rlkey=33ragg4p6x9rx65t9yvi5kewe&dl=0__;!!G_uCfscf7eWS!btLKhnEiyp5gMQfSDnHdxqgt2ie5vcVHW7e142vokJ-wEX6zZSIOcAyHsf5THg9ZlyyIsx7Vfm27ycKWAQg1_cysDdnW65aCQA$>
>
> Sincerely,
> Jesse Walters
>
> -- 
> Jesse B. Walters
> Ambizione Fellow
> Institut für Geologie
> Universität Bern
>
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