[Ifeffit] Find white line position

Carlo Segre segre at iit.edu
Thu Aug 2 09:48:02 CDT 2018

Hi Hiroshi,

You are probably better off putting a bit more time into the analysis and 
simply fitting with an arctangent and a gaussian to get the white line 


On Thu, 2 Aug 2018, Bruce Ravel wrote:

> It's not very sophisticated.
> Starting with the "flattened" spectrum (see 
> http://bruceravel.github.io/demeter/documents/Athena/bkg/norm.html#the-flattening-algorithm), 
> it simply finds the highest point in the spectrum.  Literally just the 
> ceiling function.
> The flattened spectrum is used rather than the normalized spectrum because 
> the curvature of the post-edge (or even the curvature of the pre-edge in 
> fluorescence data with a energy dispersive detector) could result in other 
> regions being higher in value than the white line.
> This is a pretty horrible algorithm.  It is, I think, guaranteed to find an 
> obviously wrong point for a metal.  Basically it works for spectra with a 
> white line and it will almost certainly fail for spectra without a white 
> line.
> Use with caution!
> HTH,
> B
> On 08/02/2018 01:28 AM, Hiroshi OJI wrote:
>> Dear all,
>> I have a question about one of the useful function, "find white line
>> position" in Athena.
>> Could anyone tell me how Athena find the white line position by this
>> function? In other words, I would like to know the algorithm to find the
>> white line position in Athena.
>> Thank you very much for your help, in advance.
>> Best regards,
>> Hiroshi Oji

Carlo U. Segre -- Duchossois Leadership Professor of Physics
Interim Chair, Department of Chemistry
Director, Center for Synchrotron Radiation Research and Instrumentation
Illinois Institute of Technology
Voice: 312.567.3498            Fax: 312.567.3494
segre at iit.edu   http://phys.iit.edu/~segre   segre at debian.org

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