[Ifeffit] Help in background removal with Athena

Tue Sep 6 09:55:23 CDT 2016

Dear Fred,

Thank you for the quick answer. Which range should I have for the EXAFS analysis to be meaningful? Like 200eV above the edge?

Thanks again,

Irina.

________________________________
From: Ifeffit <ifeffit-bounces at millenia.cars.aps.anl.gov> on behalf of fred.mosselmans at diamond.ac.uk <fred.mosselmans at diamond.ac.uk>
Sent: 06 September 2016 03:27:43
To: ifeffit at millenia.cars.aps.anl.gov
Subject: Re: [Ifeffit] Help in background removal with Athena

-----Original Message-----
From: Ifeffit [mailto:ifeffit-bounces at millenia.cars.aps.anl.gov] On Behalf Of ifeffit-request at millenia.cars.aps.anl.gov
Sent: 06 September 2016 14:57
To: ifeffit at millenia.cars.aps.anl.gov
Subject: Ifeffit Digest, Vol 163, Issue 6
Dear Irina,

Your efforts are probably sadly in vain. C K-edge NEXAFS or XANES is common, but the data range is rarely long enough for exafs analysis. You have ca 160 eV of data that is not enough for EXAFS analysis. Hence I don't think there is a way to get a good background and then FT for your data. Certainly looking at your data the noise level and thus uncertainty in which features are real and which may not be will probably prevent anything but a XANES analysis. There probably is an oscillation there but with the limited data range getting meaningful numbers from a fit is most unlikely.

Best wishes
Fred

Send Ifeffit mailing list submissions to
        ifeffit at millenia.cars.aps.anl.gov

To subscribe or unsubscribe via the World Wide Web, visit
        http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit
or, via email, send a message with subject or body 'help' to
        ifeffit-request at millenia.cars.aps.anl.gov

You can reach the person managing the list at
        ifeffit-owner at millenia.cars.aps.anl.gov

When replying, please edit your Subject line so it is more specific than "Re: Contents of Ifeffit digest..."

Today's Topics:

   1. Help in background removal with Athena (Irina Pi)

----------------------------------------------------------------------

Message: 1
Date: Tue, 6 Sep 2016 13:56:19 +0000
From: Irina Pi <Irina.Pi at icfo.eu>
To: "ifeffit at millenia.cars.aps.anl.gov"
        <ifeffit at millenia.cars.aps.anl.gov>
Subject: [Ifeffit] Help in background removal with Athena
Message-ID:
        <VI1PR0601MB22877AFA6B07BEE3CFDCEC798DF90 at VI1PR0601MB2287.eurprd06.prod.outlook.com>

Content-Type: text/plain; charset="iso-8859-1"

Dear all,

I am sorry to bother you with my tiny problems, but I have been struggling with it for a long time. The thing is I have XAS data from a graphite sample, and I don't know if I'm plotting the background correctly in it with Athena software, which determines a lot the response in the Fourier transform, and thus in our results.

I'm attaching the data as data_exafs.txt, and also two different Athena projects of different backgrount fittings, graphite_exafs1.prj and graphite_exafs2.prj. Just in case projects cannot be seen, I'm also attaching screenshots (1-01deg.png and 2-01deg.png) of the different background fittings and the parameters used in Athena in only one set of data (01deg), because they are the same in the others (02deg and 35deg). Also, the final R-space plot in both fittings are sent (1-rspace.pdf and 2-rspace.pdf).

What I wanted to ask is why it is so different the result according to the background removal. And are they correct the fittings I've done?

I would like to have a background line similar to the other figure attached (0deg.pdf, but take into account that it is from different data), but I cannot get it. I guess this last fitting seems better, doesn't it?

What could I do to have good results in the Fourier transform?

Again, sorry but I don't have much experience and it seems to be so subjective that I fear doing it all wrong.

Thank you very much,

Best regards,

Irina Pi Jauma.

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://millenia.cars.aps.anl.gov/pipermail/ifeffit/attachments/20160906/a926efd4/attachment.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: 0deg.pdf
Type: application/pdf
Size: 26131 bytes
Desc: 0deg.pdf
URL: <http://millenia.cars.aps.anl.gov/pipermail/ifeffit/attachments/20160906/a926efd4/attachment.pdf>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: 1-01deg.png
Type: image/png
Size: 168715 bytes
Desc: 1-01deg.png
URL: <http://millenia.cars.aps.anl.gov/pipermail/ifeffit/attachments/20160906/a926efd4/attachment.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: 1-rspace.pdf
Type: application/pdf
Size: 26163 bytes
Desc: 1-rspace.pdf
URL: <http://millenia.cars.aps.anl.gov/pipermail/ifeffit/attachments/20160906/a926efd4/attachment-0001.pdf>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: 2-01deg.png
Type: image/png
Size: 228473 bytes
Desc: 2-01deg.png
URL: <http://millenia.cars.aps.anl.gov/pipermail/ifeffit/attachments/20160906/a926efd4/attachment-0001.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: 2-rspace.pdf
Type: application/pdf
Size: 26113 bytes
Desc: 2-rspace.pdf
URL: <http://millenia.cars.aps.anl.gov/pipermail/ifeffit/attachments/20160906/a926efd4/attachment-0002.pdf>
-------------- next part --------------
An embedded and charset-unspecified text was scrubbed...
Name: data_exafs.txt
URL: <http://millenia.cars.aps.anl.gov/pipermail/ifeffit/attachments/20160906/a926efd4/attachment.txt>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: graphite_exafs1.prj
Type: application/octet-stream
Size: 15959 bytes
Desc: graphite_exafs1.prj
URL: <http://millenia.cars.aps.anl.gov/pipermail/ifeffit/attachments/20160906/a926efd4/attachment.obj>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: graphite_exafs2.prj
Type: application/octet-stream
Size: 15956 bytes
Desc: graphite_exafs2.prj
URL: <http://millenia.cars.aps.anl.gov/pipermail/ifeffit/attachments/20160906/a926efd4/attachment-0001.obj>

------------------------------

Subject: Digest Footer

_______________________________________________
Ifeffit mailing list
Ifeffit at millenia.cars.aps.anl.gov
http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit
Unsubscribe: http://millenia.cars.aps.anl.gov/mailman/options/ifeffit

------------------------------

End of Ifeffit Digest, Vol 163, Issue 6
***************************************

--
This e-mail and any attachments may contain confidential, copyright and or privileged material, and are for the use of the intended addressee only. If you are not the intended addressee or an authorised recipient of the addressee please notify us of receipt by returning the e-mail and do not use, copy, retain, distribute or disclose the information in or attached to the e-mail.
Any opinions expressed within this e-mail are those of the individual and not necessarily of Diamond Light Source Ltd.
Diamond Light Source Ltd. cannot guarantee that this e-mail or any attachments are free from viruses and we cannot accept liability for any damage which you may sustain as a result of software viruses which may be transmitted in or with the message.
Diamond Light Source Limited (company no. 4375679). Registered in England and Wales with its registered office at Diamond House, Harwell Science and Innovation Campus, Didcot, Oxfordshire, OX11 0DE, United Kingdom

_______________________________________________
Ifeffit mailing list
Ifeffit at millenia.cars.aps.anl.gov
http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit
Unsubscribe: http://millenia.cars.aps.anl.gov/mailman/options/ifeffit
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://millenia.cars.aps.anl.gov/pipermail/ifeffit/attachments/20160906/53969ed2/attachment-0001.html>