[Ifeffit] how to import this kind of XAFS data

[Carlo Segre]

Hi Chang:

If it is the right form, I have a Python program which will convert them 
along with a description of the file format.  I have attached the 
description below and the python program to the email.  If it does not get 
through the mailing list filter, just email me directly and I will send 
it.

Carlo

------------------------------------------------------------------------

The first column is in motor steps (!), and the angle is a linear function
of motor steps, and the rest is just Bragg's law.  Things are referenced
physically to the copper edge.

Key parameters used in the data acquisition program are in the header: 
dspace is obvious, stepdeg is steps per degree in the mono, cuedge is 
the position of the Cu edge as measured in motor step units.

I think the channel offsets (dark currents) are already subtracted from the
other columns; the offsets are just listed for documentation.

In addition, there are two different file types, the ones which have a
header beginning with NPTS and containing DSPACE and the older files which
begin with CUEDGE and do not contain d-spacing information.

For the latter, we make the following assumptions:
 	dSpacing = 1.92017
 	stepDegree = 2000 * int(edgeCu / 42000)

The guts of the calculation are as follows:

     theta = ((steps - edgeCu) / stepDegree) * (pi / 180.) + thetaCu
     energy = hc / (2 * d * numpy.sin(theta))

where	steps - the current step value in the original file
 	edgeCu - the position of the Cu edge in steps
 	stepDegree - the steps per degree theta
 	thetaCu - the angle of the Cu edge (from d-spacing information)


On Fri, 8 Dec 2017, woschangqiang at 126.com wrote:

> Hello, dear everyone.
> I downloaded a XAFS data about mettalic Ru from the website of ixs.iit.edu. There are 4 groups of information in the data, and each ranges between ~67800 with ~63000 in energy. So how to import the data to Athena, and how this kind of data was produced? Does anyone  come across this situation? Thanks for your time and help in advance.
>
> Q. CHANG
> Unversity of Chinese  of Academy of Sciences
>

-- 
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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