[Ifeffit] background removal - spline range kmin

[Matt Newville]

Hi Zhipeng Regen Lan,

On Thu, Apr 18, 2013 at 7:53 AM, Reagen Lan <reagen.lan at gmail.com> wrote:
> Dear all,
>
> For removing the background from a spec with sharp white-line, I understand
> it is often to put larger value for kmin of Spline range in Athena.
> However, in my current case, there is a intensive XANES peak at c.a. 16ev
> after the white-line peak. Thus, should I input kmin in between these two
> peaks (see attached figure test1.png)? or increase kmin to avoid the second
> strong peak(attached figure test2.png)? The two conditions do give different
> chi(R). Please could some body advise?
>
> Thanks a lot!
>
> Best regards,
> Zhipeng

Sorry for the delay.  I would not put kmin as high as you have it in
the second figure.  I tend to leave kmin=0 unless convinced otherwise.
 But,  for a white line of sulfur I would tend to simply treat all the
data as XANES and only worry about trying to normalize the spectra
(which, for this data, looks pretty challenging) and not even try to
extract chi(k).

--Matt