- Ifeffit - millenia.cars.aps.anl.gov

Log-Ratio
by Jörg Haug 05 Dec '07

05 Dec '07

Dear all, i have a question to the Log-Ratio/Phase-Differnce Analysis in Athena. What means the parameter 2pi jump? I did not find any help file for the ratio method. Best regards Jörg Haug

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Check out my Facebook profile
by Tonya Vitova 02 Dec '07

02 Dec '07

Hi Ifeffit, I set up a Facebook profile with my pictures, videos and events and I want to add you as a friend so you can see it. First, you need to join Facebook! Once you join, you can also create your own profile. Thanks, Tonya Here's the link: http://www.facebook.com/p.php?i=681514113&k=43GU3Z663WTO6FLGSAXY&r&v=2 ___________________ This e-mail may contain promotional materials. If you do not wish to receive future commercial mailings from Facebook, please click on the link below. Facebook's offices are located at 156 University Ave., Palo Alto, CA 94301. http://www.facebook.com/o.php?u=804872375&k=3da3f5

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negative amplitude
by Wojciech Starosta 30 Nov '07

30 Nov '07

Sorry if it is FAQ. But I spent some time on fitting without success and have not found answer to this. Does anybody could explain me if negative value of amplitude has any sense. I can get beautiful plot after fit, but unfortunately the message appear concerning negative value of amplitude (amplitudes). How to avoid it. Any written material will be very helpful. I know that I can define amplitude as squared value of new variable. But sometimes it does not work. Ifeffit stops with message that value of this variable cannot be determined With the best regards Wojtek Starosta Institute of Nuclear Chemistry and Technology 03-195 Warsaw, Dorodna 16 Institute of Nuclear Chemistry and Technology --- avast! Antivirus: Outbound message clean. Virus Database (VPS): 0649-1, 2006-11-18 Tested on: 2007-11-30 13:45:41 avast! - copyright (c) 1988-2007 ALWIL Software. http://www.avast.com

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(no subject)
by Bindu R. 27 Nov '07

27 Nov '07

could you tell me how does one tune the bond angles from the multiple scattreing paths? Bindu Dr.Bindu R. Visiting Scientist DCMP&MS Tata Institute of Fundamental Research Homi Bhabha Road Colaba Mumbai-400 005 India Mobile-919892536830 --------------------------------- Chat on a cool, new interface. No download required. Click here.

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Exafs distance resolution
by Eric Breynaert 27 Nov '07

27 Nov '07

Dear all, Is there a physical limitation determining exafs bond distance resolution? Very often the equation r = pi / 2 deltak is quoted as a measure for bond distance resolution. But as i understand this equation is related to the fourier transform traditionally used for exafs analysis. If exafs fitting is done in k-space, on the raw exafs data without applying fourier or any other filtering transformation is there a physical limitation determining exafs bond distance resolution? This question comes down to the following practical problem. If one has a theoretical model developed using computational chemistry that predicts two different bond lengths within one shell, e.g. an octahedral metal center surrounded by 6 oxygen atoms and this shell is predicted to be split in three subshells for wich the bond length differs only 0.05 angstroms; and this model can be fit very well in k-space with the splitted shell, off course keeping the number of fit parameters below the nyquist criterion. Is there in such a case any physical reason not to fit the experimental data with the splitted shell , but with an averaged 6-atom shell with a larger Debye Waller factor? Best regards, Eric Breynaert

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Re: [Ifeffit] Exafs distance resolution
by Frenkel, Anatoly 27 Nov '07

27 Nov '07

Yes and a very important one - see Ed Stern's talk at the 2001 EXAFS workshop "advanced methods and tricks etc. " His talk is online. Anatoly -----Original Message----- From: ifeffit-bounces(a)millenia.cars.aps.anl.gov <ifeffit-bounces(a)millenia.cars.aps.anl.gov> To: ifeffit(a)millenia.cars.aps.anl.gov <ifeffit(a)millenia.cars.aps.anl.gov> Sent: Tue Nov 27 04:44:48 2007 Subject: [Ifeffit] Exafs distance resolution Dear all, Is there a physical limitation determining exafs bond distance resolution? Very often the equation r = pi / 2 deltak is quoted as a measure for bond distance resolution. But as i understand this equation is related to the fourier transform traditionally used for exafs analysis. If exafs fitting is done in k-space, on the raw exafs data without applying fourier or any other filtering transformation is there a physical limitation determining exafs bond distance resolution? This question comes down to the following practical problem. If one has a theoretical model developed using computational chemistry that predicts two different bond lengths within one shell, e.g. an octahedral metal center surrounded by 6 oxygen atoms and this shell is predicted to be split in three subshells for wich the bond length differs only 0.05 angstroms; and this model can be fit very well in k-space with the splitted shell, off course keeping the number of fit parameters below the nyquist criterion. Is there in such a case any physical reason not to fit the experimental data with the splitted shell , but with an averaged 6-atom shell with a larger Debye Waller factor? Best regards, Eric Breynaert _______________________________________________ Ifeffit mailing list Ifeffit(a)millenia.cars.aps.anl.gov http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit

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(no subject)
by Bindu R. 27 Nov '07

27 Nov '07

Could you tell me how does one gets the information about bond angles? or How does one tune the bond angles in the artemis software? Bindu Dr.Bindu R. Visiting Scientist DCMP&MS Tata Institute of Fundamental Research Homi Bhabha Road Colaba Mumbai-400 005 India Mobile-919892536830 --------------------------------- Now you can chat without downloading messenger. Click here to know how.

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GaN atoms imput page
by codruta.zoican＠yale.edu 26 Nov '07

26 Nov '07

Dear All, Does anyone have an atoms imput page for GaN. I was trying to construct one myself to run a fitting in Artemis but I'm having some difficulties. Thank you, Codruta.

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Reply:Ifeffit Digest, Vol 57, Issue 20
by 于志国 24 Nov '07

24 Nov '07

Dear prof: I have received your answer,thank you very much! I'll try it ,if i still can not use it ,i will post it to you! Yours sincerely! yuzhiguo

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excuse me!
by 于志国 23 Nov '07

23 Nov '07

Dear prof: I am a postgraduated student in envirnmental science,so i have litte knowlege of this field ,now,i want to use athena to process date of XANES from Bsrf. but which format can be used in athena? my data format is xxxx.dat ,how can i to convert it to fit athena! Thank you very much! yuzhiguo

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