Thanks a lot Lello and Matt,
Now, it is clear to us that we anyway need our own program to automatically treat the big data set.
I tried XOP with XAID extension following your suggestions, it is nice to have the graphic operation, but for a big data set with thousands of spectra we need a program. Since we have already part of the program and hope we will finish it soon to a kind of platform for automatic data analysis.
Regards,
Qingyu
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Message: 1 Date: Fri, 30 Mar 2012 18:32:49 +0000 From: KONG Quingyu
To: "ifeffit@millenia.cars.aps.anl.gov" Subject: Re: [Ifeffit] Ifeffit Digest, Vol 109, Issue 21 Message-ID: < 30F62EE734A9EA45A3F211513CB6200324BD1922@SUN-DAG1.synchrotron-soleil.f r> Content-Type: text/plain; charset="iso-8859-1"
Thank you for all your helpful suggestions.
Actually, our beamline has recently installed a fast detector with a repetation of 20KHz, which could collected data in a time resolution of few tens of microsecond and could easily produce a large amount of data. We have already accepted three users for microsecond time resolved studies, each of them collected millions of spectra.
Together with the company that provide the detector and our software engineer we started to write a Python program to treat the data from November last year, however our engineer quitted recently, this make us to look for other solutions.
If Demeter would works well for large amount of data treatment, it would be great. As I know ID24 at ESRF has also installed the same detector and would probably have similar demanding for such a program.
Probably due to the limited memory of my pc, I can only open around 200 spectra simultanously with Athena.
Best, Qingyu Kong
Beamline ODE Soci?t? civile Synchrotron SOLEIL L'Orme des Merisiers Saint-Aubin - BP 48 91192 GIF-sur-YVETTE CEDEX Tel: +33 (0)1 69 35 97 84 (office) +33 (0)1 69 35 97 16 (beamline) email: kong@synchrotron-soleil.fr
________________________________________ From: ifeffit-bounces@millenia.cars.aps.anl.gov [ ifeffit-bounces@millenia.cars.aps.anl.gov] on behalf of ifeffit-request@millenia.cars.aps.anl.gov [ ifeffit-request@millenia.cars.aps.anl.gov] Sent: Friday, March 30, 2012 3:29 PM To: ifeffit@millenia.cars.aps.anl.gov Subject: Ifeffit Digest, Vol 109, Issue 21
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Today's Topics:
1. delr and ss parameterization (Ebrahim Rezaei) 2. program (KONG Quingyu) 3. Re: program (Carlo Segre) 4. Re: program (Matt Newville) 5. Re: delr and ss parameterization (Bruce Ravel) 6. Re: program (Bruce Ravel)
----------------------------------------------------------------------
Message: 1 Date: Thu, 29 Mar 2012 21:57:21 -0700 (PDT) From: Ebrahim Rezaei
To: ifeffit@millenia.cars.aps.anl.gov Subject: [Ifeffit] delr and ss parameterization Message-ID: <1333083441.66190.YahooMailClassic@web120501.mail.ne1.yahoo.com> Content-Type: text/plain; charset="utf-8"
Hi everyone,
I am working with bulk and nano structures of MnO, MnO2 and Mn2O3. I have two questions regarding how to parameterize delr and ss in Artemis.
It is recommended to use either delr=alfa*Reff or relate it to unit cell structure. Can anybody tell me how to do the second approach?
Also is that a good idea to let all ss to float? Or it should be constrained based on type and distance of atoms? I have seen an example about ZnO just letting the first two shell?s ss to float and let the rest to be the same. I would appreciate it very much if anybody could help me with this too.
Regards,
Ebrahim Rezaei
PhD Candidate, Chem. Eng. Dep., University of Saskatchewan
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Message: 2 Date: Fri, 30 Mar 2012 06:46:38 +0000 From: KONG Quingyu
To: "ifeffit@millenia.cars.aps.anl.gov" Subject: [Ifeffit] program Message-ID: < 30F62EE734A9EA45A3F211513CB6200324BD1794@SUN-DAG1.synchrotron-soleil.f r> Content-Type: text/plain; charset="iso-8859-1"
We recently collected 3000 EXAFS spectra to follow a chemical reaction process, we would like to fit the experimental data with reference spectra using linear combination fitting. Does anyone know there are available or commercial program to normalize the data and make linear combination fitting. We tried to do it with Athena manually, but 3000 spectra take a long time for us and it is not a practical way.
Thanks a lot.
Qingyu Kong
Beamline ODE Soci?t? civile Synchrotron SOLEIL L'Orme des Merisiers Saint-Aubin - BP 48 91192 GIF-sur-YVETTE CEDEX Tel: +33 (0)1 69 35 97 84 (office) +33 (0)1 69 35 97 16 (beamline) email: kong@synchrotron-soleil.fr
------------------------------
Message: 3 Date: Fri, 30 Mar 2012 01:56:57 -0500 (CDT) From: Carlo Segre
To: XAFS Analysis using Ifeffit Subject: Re: [Ifeffit] program Message-ID: Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Hi Qingyu
On Fri, 30 Mar 2012, KONG Quingyu wrote:
We recently collected 3000 EXAFS spectra to follow a chemical reaction process, we would like to fit the experimental data with reference spectra using linear combination fitting. Does anyone know there are available or commercial program to normalize the data and make linear combination fitting. We tried to do it with Athena manually, but 3000 spectra take a long time for us and it is not a practical way.
You might wish to look into Bruce Ravel's new suite of programs (called Demeter). I believe they are built to allow easy scripting of massive quantities of data such as yours.
Carlo
-- Carlo U. Segre -- Duchossois Leadership Professor of Physics Associate Dean for Graduate Admissions, Graduate College Illinois Institute of Technology Voice: 312.567.3498 Fax: 312.567.3494 segre@iit.edu http://phys.iit.edu/~segre segre@debian.org
------------------------------
Message: 4 Date: Fri, 30 Mar 2012 07:56:05 -0500 From: Matt Newville
To: XAFS Analysis using Ifeffit Subject: Re: [Ifeffit] program Message-ID:
Content-Type: text/plain; charset=ISO-8859-1
Hi Qingyu,
We recently collected 3000 EXAFS spectra to follow a chemical reaction
On Fri, Mar 30, 2012 at 1:46 AM, KONG Quingyu
wrote: process, we would like to fit the experimental data with reference spectra using linear combination fitting. Does anyone know there are available or commercial program to normalize the data and make linear combination fitting. We tried to do it with Athena manually, but 3000 spectra take a long time for us and it is not a practical way. Ifeffit is designed to be scriptable for batch processing. This can be done with a raw Ifeffit script (which isn't very flexible) or from Perl or Python, which are more flexible. Carlo mentioned Demeter, which is a high-level Perl wrapping of the lower-level functionality. Working with 3000 spectra may be challenging with Ifeffit version 1.2, as the total amount of available memory is limited, but with some care it should be possible.
FWIW, the next version of Ifeffit will eliminate this memory limitation, and make both scripting and extending the functionality much easier and better. This is still a work in progress (see https://github.com/xraypy/xraylarch) and poorly documented, but the essential idea is to write all of Ifeffit's functionality in Python, for all the reasons just stated, and this far enough along that I am confident it will be a big improvement. So far (for XAFS), this can read data, do simple pre-edge subtraction, normalization, remove backgrounds ala autobk, and do XAFS Fourier transforms. It can do simple "general purpose fitting", but does not yet expose a simple-to-use linear combination fitting functionality (shouldn't be too hard, as all the linear algebra pieces are readily available) or fitting spectra to Feff calculations (a bit more involved). Work is slow (mostly due to other obligations), but progress is being made, and it's close to ready for an initial release. If you are (or anyone else is) interested in trying this or helping out, let me know.
--Matt
------------------------------
Message: 5 Date: Fri, 30 Mar 2012 09:13:11 -0400 From: Bruce Ravel
To: XAFS Analysis using Ifeffit Subject: Re: [Ifeffit] delr and ss parameterization Message-ID: <201203300913.12166.bravel@bnl.gov> Content-Type: Text/Plain; charset="utf-8" On Friday, March 30, 2012 12:57:21 am Ebrahim Rezaei wrote:
I am working with bulk and nano structures of MnO, MnO2 and Mn2O3. I have two questions regarding how to parameterize delr and ss in Artemis.
It is recommended to use either delr=alfa*Reff or relate it to unit cell structure. Can anybody tell me how to do the second approach?
Also is that a good idea to let all ss to float? Or it should be constrained based on type and distance of atoms? I have seen an example about ZnO just letting the first two shell?s ss to float and let the rest to be the same. I would appreciate it very much if anybody could help me with this too.
The alpha*reff trick is only strictly valid for cubic, monoatomic materials. For everything else in the world, it is an increasingly poor approximation. That's not to say it is not a helpful parameterization, just that you need to be mindful of its limitations.
As for the sigma^2 parameter, you have to balance when is physically reasonable with what can be reliably extracted from a real data analysis.
- Two atoms of a different species at the same distance should have different sigma^2 because they have different masses.
- Two atoms of the same species at different distances should have different sigma^2 because sigma^2 is a mean square deviation in distance.
So, in some sense, all scatterers might have their own sigma^2 parameters. But that is not to say that you data are sufficient to independently determine that many parameters. When you run up against the limited information content of your data, that is when you start making approximations of the sort that lead to setting sigma^2 parameters for different scatterers to be the same.
However, there are sensible and physically justifiable reasons why the sigma^2 for certain multiple scattering paths should be related to those of single scattering paths. See http://dx.doi.org/10.1103/PhysRevB.54.156
Two of my favorite papers that show excellent data analysis solving real-world problems and which are written in a way that is of pedagogical value for XAS beginners are Scott Calvin's paper on doped ferrites (http://dx.doi.org/10.1103/PhysRevB.66.224405) and Shelly Kelly's paper on uranyl binding to biomass (http://dx.doi.org/10.1016/S0016-7037(02)00947-X). For more interesting papers, look through the archives of the mailing list and see who gives good answers to questions, then look up their papers.
Another extremely useful resource which includes extensive discussion of the sorts of things you are asking about is Shelly's review chapter. Here's the amazon link to that book:
http://www.amazon.com/Methods-Soil-Analysis-Part-Mineralogical/dp/0891 188460/ The book is a bit pricy, but if you are a clever googler, you may find a PDF copy of her chapter.
Regards, B
--
Bruce Ravel ------------------------------------ bravel@bnl.gov
National Institute of Standards and Technology Synchrotron Methods Group at NSLS --- Beamlines U7A, X24A, X23A2 Building 535A Upton NY, 11973
My homepage: http://xafs.org/BruceRavel EXAFS software: http://cars9.uchicago.edu/ifeffit/Demeter
------------------------------
Message: 6 Date: Fri, 30 Mar 2012 09:29:10 -0400 From: Bruce Ravel
To: XAFS Analysis using Ifeffit Subject: Re: [Ifeffit] program Message-ID: <201203300929.11143.bravel@bnl.gov> Content-Type: Text/Plain; charset="iso-8859-1" On Friday, March 30, 2012 02:46:38 am KONG Quingyu wrote:
We recently collected 3000 EXAFS spectra to follow a chemical reaction process, we would like to fit the experimental data with reference spectra using linear combination fitting. Does anyone know there are available or commercial program to normalize the data and make linear combination fitting. We tried to do it with Athena manually, but 3000 spectra take a long time for us and it is not a practical way.
Hi Qingyu,
Carlo is correct, Demeter could be used to write a special purpose program for automating this sort of thing. The performance in terms of speed may not be exactly what you want, but the performance in terms of quickly prototyping a program to process and analyze a large data volume is excellent.
The Demeter code base comes with extensive (although still incomplete) documentation as well as plenty of example scripts, including examples for the individual chores you mention above.
Here's Demeter's documentation: http://bruceravel.github.com/demeter/
As a closing comment, isn't it somehow strange that you and your colleagues went to all the trouble of building a fancy dispersive beamline without thinking ahead about how you were going to analyze your data?
B
--
Bruce Ravel ------------------------------------ bravel@bnl.gov
National Institute of Standards and Technology Synchrotron Methods Group at NSLS --- Beamlines U7A, X24A, X23A2 Building 535A Upton NY, 11973
My homepage: http://xafs.org/BruceRavel EXAFS software: http://cars9.uchicago.edu/ifeffit/Demeter
------------------------------
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Message: 2 Date: Fri, 30 Mar 2012 16:36:58 -0500 From: Matt Newville
To: XAFS Analysis using Ifeffit Subject: Re: [Ifeffit] Ifeffit Digest, Vol 109, Issue 21 Message-ID:
Content-Type: text/plain; charset=ISO-8859-1
Hi Qingyu,
On Fri, Mar 30, 2012 at 1:32 PM, KONG Quingyu
wrote: Thank you for all your helpful suggestions.
Actually, our beamline has recently installed a fast detector with a repetation of 20KHz, which could collected data in a time resolution of few tens of microsecond and could easily produce a large amount of data. We have already accepted three users for microsecond time resolved studies, each of them collected millions of spectra.
Together with the company that provide the detector and our software engineer we started to write a Python program to treat the data from November last year, however our engineer quitted recently, this make us to look for other solutions.
Bruce wrote earlier,
As a closing comment, isn't it somehow strange that you and your colleagues went to all the trouble of building a fancy dispersive beamline without thinking ahead about how you were going to analyze your data?
Sadly, Bruce's observation is not unusual at all. Everyone is experiencing data overloads, and almost no one is investing in computing resources. Yours may be slightly larger than most XAFS users, but only by one or two orders of magnitude. Then again, you had a software engineer at your beamline at least for a while.
To be clear, Ifeffit, Athena, Demeter, Sixpack, and so on are written primarily by beamline scientists like yourself. Your choices are to use what someone else gives you, write your own, or hire someone to do it for you. It appears that the last choice rarely works very well. That you get to use Bruce's codes at all (and for free!) is not an accident: it is part of the design, and an outcome of the programs being written by beamline scientists.
The current software base is more than ten years old, and showing its age especially with respect to large data sets and multiple processors. This is a really good opportunity for you and your colleagues (and others in similar situations) to join in. That is, you should write code to deal with your fast data rates. If you write that with the Ifeffit family of programs, not only will people at ESRF be able to use it, but so will anyone else.
If Demeter would works well for large amount of data treatment, it would be great. As I know ID24 at ESRF has also installed the same detector and would probably have similar demanding for such a program.
Looking into Demeter is one option, though I don't know exactly that is perfect for the linear combination analysis you want to use. Most of the core algorithms in Demeter still use Ifeffit 1.2, which are going to be limited for your needs, though they can be worked around if careful. Transferring Demeter to use the newer Ifeffit2 should be possible, but neither Bruce or I have done more than proof-of-principle tests. Looking into using Larch / IFeffit2 might be better for you, and I'd be happy to help you do that. For one thing, this approach has no memory limitations beyond your machine, is in Python and can read HDF5 files (which SOLEIL uses, as far as I understand) directly. It also has the possibility of using multicore machines well, but this has not yet been automated. It is also possible that the linear algebra techniques used for x-ray fluorescence map analysis, including code from Gerd Wellenreuther and Armando Sole would be useful for your needs.
Probably due to the limited memory of my pc, I can only open around 200 spectra simultanously with Athena.
You almost certainly want to not use Athena here anyway. You want automated processing programs.
Like Bruce hinted at, you've invested heavily in a detector that allows you to collect data at a rate orders of magnitude faster than you could before. It would have been incredibly naive to believe that decade-old software would have been able to keep up with that. This is a good opportunity for you to help out yourself and others.
Cheers,
--Matt
------------------------------
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End of Ifeffit Digest, Vol 109, Issue 23 ****************************************
-- Carmelo Prestipino Sciences Chimiques de Rennes UMR 6226 Solid State and Materials Chemistry group (CSM) Campus de Beaulieu, B?t 10B, bureau 122 F-35042 RENNES France Tel: (+33) 22323 6531 FAX: (+33) 22323 5959