[Ifeffit] Athena Peak Fitting

[Matt Newville]

Hi Jenny,

I would say that method 2 looks better, as the fit over the whole of
the specified fitting range is clearly better.   I wouldn't
necessarily say that "peak 1" in this fit -- I'm assuming you mean the
highest energy peak at ~2488.3eV -- is  too broad.  At that high
energy (definitely into the EXAFS region),  the idea of peaks coming
from specific electronic transitions breaks down, and EXAFS
oscillations can be that broad in energy.

It seems that you need this "broad peak" because you're fitting out
past 2500 eV.    I think that's OK (that third broad peak may not be a
single electronic transition but is still useful for identifying
species).  But, if you'd rather not have to use the broader peak, you
might also try fitting just the two sharper peaks at lower energy, say
out to 2485 eV.

Hope that helps,

--Matt




On Wed, Oct 1, 2008 at 1:31 PM, Jenny Cai <jennyh_cai at yahoo.ca> wrote:
> Hi Everyone,
>
> I am using Athena peak fitting function to fit the sulfur spectrum of my
> coke sample. I checked everywhere, but couldn't get detailed instruction for
> using this function. So, I attached a file with this email to get help.
> Could you please take a look at it, and tell me if I did the fitting right
> (in terms of fitting procedure only)?
>
> I did the fitting in two ways, and I know both of them have problems. For
> instance, in the first case, I can't get a good step line and have to cut
> off the tail of the spectrum. In the second one, peak 1 is way too broad,
> but if I cut it off, the fitting will be very poor. So, please tell me which
> way is better, or you have some ideas to improve the fitting.
>
> Thank you in advance!
>
>
> Best,
>
> Jenny
>
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