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
On Fri, Dec 8, 2017 at 3:00 AM, woschangqiang@126.com wrote: Hello, dear everyone.
I downloaded a XAFS data about mettalic Ru from the website of *ixs.iit.edu
http://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. This data file is a particularly nasty form of data from the Lytle
database. Each line of data contains consecutive pairs of AngleSteps Mu
To convert the angle steps to energy, you need to know how many steps there
are in a degree and the lattice constant of the mono crystal used. Neither
of these are in the file. I happen to have a good guess that these numbers
should be 8000 steps per degree, and 1.92017 Angstroms.
Still the data are a pain to deal with. They can be read with Ifeffit too,
but with Larch it goes like this:
ru = read_ascii('ru.001.txt')
# flatten array data to [step, mu, step, mu,...]
dat = ru.data.transpose().flatten()
# take every 2nd value as angle or xmu
asteps = dat[0::2]
xmu = dat[1::2]
step2rad = (pi/180)/ 8000 # radians per step
hc = 12398.417 # eV Ang
dspace = 1.92017 # Ang
energy = hc/(2*dspace)/sin(asteps * step2rad)
label = 'energy xmu angle_steps'
header = ['data converted from Lytle database file: %s' % ru.filename,
'using dspace=1.92017, steps-per-degree=8000']
write_ascii('ru.001.xmu', energy, xmu, asteps, header=header,
label=label)
Resulting converted file attached.
--Matt
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@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@iit.edu http://phys.iit.edu/~segre segre@debian.org
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