March 2004 - Ifeffit - millenia.cars.aps.anl.gov

*****SPAM***** references for self-absorption correction
by Grant Bunker 01 Mar '04

01 Mar '04

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question about S02 (passive electron reduction factor)
by hsnuboy 01 Mar '04

01 Mar '04

Dear Ifeffit folks, This is Yu-Chuan. I am now trying to fit my sample, magnesium orthovanadate. I try to follow Bruce's Cu example and Scott's ZnO example steps and I found a problem come to my fitting. At the beginning of the fitting, the S02(amp) are far away from 0.9 (just about 0.3). It's much different than Bruce's and Scott's examples. For Cu and ZnO examples, the fitting results of amp are close to 0.9 at the beginning even if you set just four parameters (guess:amp, e0, delr, and ss). Also, John have said that the S02 value should be around 0.9. That's why I am wondering if there is anything wrong with my data processing? Does anyone happen to have this kind of problem? Thank you for your help. Good day Yu-Chuan

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RE: [Ifeffit] question about S02 (passive electron reduction factor)
by hsnuboy 29 Feb '04

29 Feb '04

Scott, Bruce, Matt, Kelly, Grant and all, Thank you for your advice. I am really appreciate that.I think I have to give more detail about my analysis results and make it more clear. 1. I took the fluorescence spectrum. 2. I checked the pre-edge and post-edge lines and they looked reasonable. 3. I took the three first shell paths(Vanadium-Oxide) to fit the data. and I set amp, e0, delr, ss for the variables. 4. The degeneracy of the paths are the same as calculated by FEFF6 5. the following results amp = 0.316 +/- 0.108 e0 = 5.053 +/- 4.321 delr= 0.003 +/- 0.025 ss = -0.003 +/- 0.004 6. the correlations between amp and ss =0.88 e0 and delr = 0.86 I don't know if any other information can help to solve this problem. Thank you for your help. By the way, Grant, the papaer you mentioned, is that from " J. J. Rehr, C. H. Booth, F. Bridges, and S.I. Zabinsky, Physical review B, 49,12347, 1994"? Or other else? Can you give me more detail about that? Good day Yu-Chuan

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