Hi Ken,
Our work seems pretty similar in terms of peak fitting C K-edge spectra of
organic compounds with Athena, as I dealt with this throughout my PhD
programme.
The answer is positive, you can do peak fitting restrained only to a certain
fitting range that you choose.
So, in order to do this, you can choose the minimum and maximum values of the
fit range from the Peak Fitting window in Athena (you can either use the pluck
buttons and choose the points on the plots window, or enter them manually).
After you set the fit range that strictly contains the position of the peak you
want to fit (preferably it shall not contain other peaks), you just need to
tick the parameters that you want to keep fixed for that specific peak
(including other peaks you do not want to change the fitting parameters for).
For example, if you want to keep fixed the height/amplitude or width of the
peak of interest, you need to tick these corresponding boxes and leave
un-ticked the box containing the energy position (E0).
Once you are finished with one peak, you can continue the same procedure with
the rest of the peaks in your spectrum.
This is a way faster method to fit peaks in an effective way, and it usually
works fine - sometimes you still need to make some manual adjustments to the
parameters to convince yourself whether the fits can be done better or not.
I hope this helps a bit.
Regards,
Adrian
***
Adrian Gainar
PhD student
Office: D37
School of Chemical Engineering and Analytical Science
Jackson's Mill
University of Manchester
Manchester
M13 9PL
UK
e-mail address contact: adrian.gai...@postgrad.manchester.ac.uk
office telephone no.: +44(0)161 306 4362
From: ifeffit-boun...@millenia.cars.aps.anl.gov
[ifeffit-boun...@millenia.cars.aps.anl.gov] on behalf of Kenneth Latham
[kenneth.lat...@uon.edu.au]
Sent: 28 July 2015 05:59
To: ifeffit@millenia.cars.aps.anl.gov
Subject: [Ifeffit] Setting ranges in peak fitting
Hi Bruce,
To clarify this further, I am peak fitting a number of peaks under the carbon
edge. For example, I know from the literature that the 1s-p transition for the
C=C should be located between 284.5 to 285.5 eV, so I would fit a peak at about
285 eV to start with. I would then move on to fitting additional peaks based on
their literature values with what I know about the material/where obvious peaks
are in the NEXAFS.
The problem now comes when I tell Athena to fit, it will start to move the
peaks all over the place to obtain the best fit, typically placing them in
locations where functionalities don't appear under the NEXAFS. In other words,
it would move peaks away from where I would expect them to be based on the
literature. This can be partially stopped by fixing all but one peak, fitting
it and then and applying this procedure to every peak multiple times.
What I was wondering is if Athena has the ability to set a range that each peak
is allowed to move, i.e., the C=C center would be restricted to values between
284.5-285.5 eV. Hence I could set up the ranges and fit quickly based on those.
Cheers,
Ken Latham
From: ifeffit-boun...@millenia.cars.aps.anl.gov
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ifeffit-requ...@millenia.cars.aps.anl.gov
Sent: Saturday, 25 July 2015 3:00 AM
To: ifeffit@millenia.cars.aps.anl.gov
Subject: Ifeffit Digest, Vol 149, Issue 23
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Today's Topics:
1. Setting ranges in peak fitting Athena (Kenneth Latham)
2. Re: Setting ranges in peak fitting Athena (Ravel, Bruce)
3. Re: Setting ranges in peak fitting Athena (Matt Newville)
--
Message: 1
Date: Fri, 24 Jul 2015 00:14:18 +
From: Kenneth Latham
To: "ifeffit@millenia.cars.aps.anl.gov"
Subject: [Ifeffit] Setting ranges in peak fitting Athena
Message-ID:
Content-Type: text/plain; charset="iso-8859-1"
Hi Bruce,
Is it possible to set a range of values that the the center (or any other
values) can be between for line shapes when peak fitting in Athena? Similar to
what you can do in CasaXPS.
If not, do you know of a program that can handle NEXAFS peak fitting and has
that feature?
Cheers,
Ken
--
Message: 2
Date: Fri, 24 Jul 2015 13:14:03 +
From: "Ravel, Bruce"
To: XAFS Analysis using Ifef
