Hello Darek,
Thank you so much for your reply.
Yes, i can rely on model, we have performed reitveld refinement to get
the crystallographic data.
To my knowledge, there should not be any other phases.
Your suggestion is quite right. Somehow, i have to constrain my
parameters (to reduce the no. of parameters) and try to fit it.
However, I would like to ask you following questions.
I am confused about the term "Delta E0"
what is the theoretical meaning of that in terms of photoelectron
interactions ?
If you have multiple atomic sites of absorbing atom, should "Delta E0"
be same for all of them (assuming all absorbing atoms are at same
oxidizing state) ?
I am looking forward to your comments..
Best regards,
Rana
On 27.07.2010 19:00, ifeffit-requ...@millenia.cars.aps.anl.gov wrote:
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Today's Topics:
1. updating Athena in Windows 7 (Monson, Todd)
2. ODP: Ifeffit Digest, Vol 88, Issue 12 (Zajac, Dariusz A.)
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Message: 1
Date: Mon, 26 Jul 2010 14:39:00 -0600
From: "Monson, Todd"<tmon...@sandia.gov>
To: "ifeffit@millenia.cars.aps.anl.gov"
<ifeffit@millenia.cars.aps.anl.gov>
Subject: [Ifeffit] updating Athena in Windows 7
Message-ID:
<ac050ba7eac9a34e9a05bc31c3aa2e8b183c0d1...@es02snlnt.srn.sandia.gov>
Content-Type: text/plain; charset="us-ascii"
On Saturday, while starting up Athena, I was informed that there was an update
to Athena available. I tried installing the update but failed. I am afraid
this is due to some user permission issue in windows 7. How can I try to
reinstall the update and ensure that it works?
Thanks,
Todd
Todd Monson
Sandia National Labs
Nanomaterials Sciences
P.O. Box 5800, MS 1415
Albuquerque, NM 87185-1415
(505) 845-2129
Fax: (505) 844-5470
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Message: 2
Date: Tue, 27 Jul 2010 17:47:36 +0200
From: "Zajac, Dariusz A."<dariusz.za...@desy.de>
To: "XAFS Analysis using Ifeffit"<ifeffit@millenia.cars.aps.anl.gov>
Subject: [Ifeffit] ODP: Ifeffit Digest, Vol 88, Issue 12
Message-ID:
<35e004ad6290a7438fca34bbf325f41601206...@adxv2.win.desy.de>
Content-Type: text/plain; charset="iso-8859-2"
Dear Rana,
sorry for really late response, but I was cut off from the internet for a
while...
if I understand correctly you created a model of the structure and you fit it
to the first shell (oxygen?), what is the expected difference between different
path? with my humble experience you can try to clarify following problems:
- is your model really correct and cover all possible scenarios?
- are you sure that in your sample are no other (unwanted) phases? with Mn, Fe
it can happen...
- have you tried to increase the number of variables? (to free the fit from
boundaries)
I am only thinking about it (with an examples at Fe site):
you have 4 positions for Fe and if there is a mixing between Fe and Mn sites
additional 3, it means maximally 7 sets of (e0, delr, and ss2 - N you can
probably estimate, calculate). that means you have more variables than
independent points. you should try, in the first approximation, to free the
delr parameter and keep others the same. I havent seen good example of fitting
such samples, but if you start from different points, and during fitting you
will minimize no. of variables with the same result (with the same fit) should
be ok.
good luck
darek
-----Wiadomo?? oryginalna-----
Od: ifeffit-boun...@millenia.cars.aps.anl.gov w imieniu Jatinkumar Rana
Wys?ano: ?r 2010-06-16 12:57
Do: ifeffit@millenia.cars.aps.anl.gov
Temat: Re: [Ifeffit] Ifeffit Digest, Vol 88, Issue 12
Dear Darek,
Sorry for the late response. To fit the "first shell" the No.of
independent points and No.of variables which i use are as follows:
I use deltaK=11, deltaR = 1.1 so No.of independent points are 8 and
No.of variables are 4 (i.e. N, e0, delr, and ss2) I set s02=0.9.
Best regards,
Rana
On 14.06.2010 19:00, ifeffit-requ...@millenia.cars.aps.anl.gov wrote:
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Today's Topics:
1. XAFS fitting with multiple atomic sites of absorbing atom
(Jatinkumar Rana)
2. ODP: XAFS fitting with multiple atomic sites of absorbing
atom (Zajac, Dariusz A.)
----------------------------------------------------------------------
Message: 1
Date: Mon, 14 Jun 2010 12:00:27 +0200
From: Jatinkumar Rana<jatinkumar.r...@helmholtz-berlin.de>
To: Ifeffit users<ifeffit@millenia.cars.aps.anl.gov>
Subject: [Ifeffit] XAFS fitting with multiple atomic sites of
absorbing atom
Message-ID:<4c15fdbb.1050...@helmholtz-berlin.de>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Dear users,
I have measured XAFS spectra on Mn and Fe edge on my material. The
material contains 3 different atomic positions for Mn and 4 different
atomic positions for Fe.
Initially, I tried fitting Fe-edge/Mn-edge spectra using indiviual Fe/Mn
atomic position one-by-one (i.e. first take one Fe/Mn position,
calculate Feff paths, consider certain paths to fit specific R-range,
then take another Fe/Mn position and do the same) but the fit was not
good visually and in terms of goodness of fit parameters.
Then, i tried fitting Fe-edge/Mn-edge spectra, taking into account all
Fe/Mn atomic position together i.e. I separately calulated Feff paths
for each Fe/Mn atomic position and summed up related paths from each
Feff calculation for fitting a specific R-range. (The assumption being,
the experimental Fe-edge/Mn-edge XAFS spectra has varying contribution
from all Fe/Mn atomic position in crystal structure).
Anybody in the group could comment about my approach to fit such problem ?
Is there any specific strategy to fit such problem ?
I would be thankful if you could suggest some literature available on
such problems.
Thanks in advance.
Best regards,
Rana
------------------------------
Message: 2
Date: Mon, 14 Jun 2010 13:34:18 +0200
From: "Zajac, Dariusz A."<dariusz.za...@desy.de>
To: "XAFS Analysis using Ifeffit"<ifeffit@millenia.cars.aps.anl.gov>
Subject: [Ifeffit] ODP: XAFS fitting with multiple atomic sites of
absorbing atom
Message-ID:
<35e004ad6290a7438fca34bbf325f41601206...@adxv2.win.desy.de>
Content-Type: text/plain; charset="iso-8859-2"
Dear Rana,
could you specify how many independent data points and variables you have and
you use for fitting?
thnx
darek
-----Wiadomo?? oryginalna-----
Od: ifeffit-boun...@millenia.cars.aps.anl.gov w imieniu Jatinkumar Rana
Wys?ano: Pn 2010-06-14 12:00
Do: Ifeffit users
Temat: [Ifeffit] XAFS fitting with multiple atomic sites of absorbing atom
Dear users,
I have measured XAFS spectra on Mn and Fe edge on my material. The
material contains 3 different atomic positions for Mn and 4 different
atomic positions for Fe.
Initially, I tried fitting Fe-edge/Mn-edge spectra using indiviual Fe/Mn
atomic position one-by-one (i.e. first take one Fe/Mn position,
calculate Feff paths, consider certain paths to fit specific R-range,
then take another Fe/Mn position and do the same) but the fit was not
good visually and in terms of goodness of fit parameters.
Then, i tried fitting Fe-edge/Mn-edge spectra, taking into account all
Fe/Mn atomic position together i.e. I separately calulated Feff paths
for each Fe/Mn atomic position and summed up related paths from each
Feff calculation for fitting a specific R-range. (The assumption being,
the experimental Fe-edge/Mn-edge XAFS spectra has varying contribution
from all Fe/Mn atomic position in crystal structure).
Anybody in the group could comment about my approach to fit such problem ?
Is there any specific strategy to fit such problem ?
I would be thankful if you could suggest some literature available on
such problems.
Thanks in advance.
Best regards,
Rana
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