[Ifeffit] phase corrections and saving files
Bruce Ravel
ravel at phys.washington.edu
Tue Nov 25 16:12:23 CST 2003
Hi folks,
I have received a few questions recently on the topic of saving data
to column data files after doing a phase corrected Fourier transform.
Both Athena and Artemis will do this. Let me explain how it works.
** In Athena, when you save chi(R) as a column data file for the
current group it will save the phase corrected chi(R) if the button
for central atom phase corrections is checked for that group.
** In Artemis, you can save chi(R) for the data, the fit, or any part
of the fit. If a path has been chosen for the phase correction on
the data page, then the Fourier transform will be done using that
path's phase correction before writing out chi(R).
** Thus the rule for both programs is simple. If you select a phase
correction, it will be applied before writing out chi(R).
** For both programs, chi(q) will likewise be written out with the
phase correction is the phase correction is chosen. That is, if
the phase correction is chosen, it will be applied to the forward
transform and the backward transform will be done on that spectrum.
** Neither program writes out a phase corrected chi(k).
** Athena uses a central atom phase correction and no scattering atom
correction. Artemis uses both a central and scattering atom phase
correction, but only that of the path selected for the correction.
The fit in Artemis is *always* done using the non-phase-corrected
data and the non-phase-corrected feffNNNN.dat files.
** There was a recent discussion on the mailing list about doing phase
*and* amplitude corrections. Neither Athena nor Artemis does that
at this time.
If you observe a situation where either program does not behave as
advertised, let me know so I can fix it for the next release.
Regards,
B
--
Bruce Ravel ----------------------------------- ravel at phys.washington.edu
Code 6134, Building 3, Room 222
Naval Research Laboratory phone: (1) 202 767 5947
Washington DC 20375, USA fax: (1) 202 767 1697
NRL Synchrotron Radiation Consortium (NRL-SRC)
Beamlines X11a, X11b, X23b
National Synchrotron Light Source
Brookhaven National Laboratory, Upton, NY 11973
My homepage: http://feff.phys.washington.edu/~ravel
EXAFS software: http://feff.phys.washington.edu/~ravel/software/exafs/
More information about the Ifeffit
mailing list