[Ifeffit] Import XAFS Data from Farrel Lytle Database (http://ixs.iit.edu/database/)
Carlo Segre
segre at iit.edu
Wed Jul 30 23:31:24 CDT 2014
Hi Peng:
I wrote a small Python program to convert these data into something more
understandable. In the process, I documented the format as far as I could
figure it out. I have included the description below:
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 Wed, 30 Jul 2014, Peng Liu wrote:
> Hi all,
>
> I searched the Farel Lytle Database and looked like I found chalcopyrite
> spectra for Cu from
> http://ixs.iit.edu/database/data/Farrel_Lytle_data/RAW/Cu/index.html.
>
> I downloaded the data, but I can not import into Athena. I looked into the
> data, it looked wired for me. The first column doesn't look like energy for
> Cu.
>
> I am wondering if anyone have any idea how to import or transfer the data. I
> attached the data file.
>
> Regards,
>
> Peng
>
>
--
Carlo U. Segre -- Duchossois Leadership Professor of Physics
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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