[Ifeffit] k-range question & R-factor

[Baker, Leslie]

Chris,

 

That double peak around 8 is normal for Fe (oxyhydr)oxides; see the
attached for an example.  Also see Toner et al. 2009 (GCA 73 p 388, Fig
6) for a nice discussion of what structures can make it show up.  I
think perhaps you are seeing an oxidation state shift too.

 

Best of luck with the happiness!

 

-Leslie

 

 

-----Original Message-----
From: ifeffit-bounces at millenia.cars.aps.anl.gov
[mailto:ifeffit-bounces at millenia.cars.aps.anl.gov] On Behalf Of
Christopher Patridge
Sent: Tuesday, January 15, 2013 6:22 AM
To: XAFS Analysis using Ifeffit
Subject: [Ifeffit] k-range question & R-factor

 

Hello Users,

 

I was looking for an opinion about the chi(k) signal in a set of data I
am analyzing.  Brief background, this is a set of in-situ XAS data
collected at the Fe K edge from a working electrochemical cell at a
range of potentials during charge; I did not collect the data. I suspect
the feature at ~ 8 angstroms-1, although present in all the spectra is
noise or glitch and wondered if I am being overly cautious?

 

My conservative range ( k = 2-7 and R = 1-2) really constrains the model
Nidp = 3.31.  Luckily, multiple datasets ( 8 ) to the rescue to give me
some flexibility.  In a multiple dataset fitting, is the R-factor of the
whole set just the average or total mismatch across all the datasets or
it calculated another way?

 

Working towards happiness,

 

Chris Patridge

 

--

********************************

Christopher J. Patridge, PhD

NRC Post Doctoral Research Associate

Naval Research Laboratory

Washington, DC 20375

Cell: 315-529-0501

 

 

**

Leslie L. Baker, Ph.D.

Department of Plant, Soil and Entomological Sciences 

and Department of Geological Sciences

University of Idaho 

875 Perimeter Drive MS 2339

Moscow, ID 83844-2339

208-885-9239

http://scholar.google.com/citations?user=ejpH5p0AAAAJ
<http://scholar.google.com/citations?user=ejpH5p0AAAAJ> 

 

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