NAME
athena - interactive XAS data processing
SYNOPSIS
athena file...
DESCRIPTION
This manpage documents the athena program, for interactive XAS data
processing, including converting raw data to mu(E), aligning, merging,
deglitching, Fourier transforming, and plotting. Basically, Athena is
intended to handle all chores involving XAS data except for
quantitative analysis by fitting to theoretical standards. Athena’s
sister program Artemis is the fitting program.
Athena has two interesting and unusual features. The first is that
there are no buttons for explicitly removing the background from mu(E)
data or for performing Fourier transforms. The only active buttons
displayed on the main window are for plotting. Athena always knows
when data requires a background removal or a Fourier transform and will
perform the necessary analysis steps before displaying the plot.
The second interesting feature is that it is just as easy to perform
analysis and plotting chores on multiple data sets as on an individual
data set. Athena automates the most common data processing chores and
automatically generates plots of one or more data sets.
SYNOPSIS
Athena is a graphical and interactive program written in the perl
programming language, using the Tk display engine, the IFEFFIT EXAFS
library, and the PGPLOT plotting library. (See below for a list of
relevant URLs.)
When Athena starts, you are presented with a window whose layout looks
something like this:
+----------------------------------------+
| menubar |
+---------------------------+------------+
| | |
| | |
| | Group |
| Group | List |
| Parameters | |
| | |
| | |
| +------------+
| | Plot crrnt |
| +------------+
| | Plot mrked |
| +------------+
| | |
| | Plot |
| | Features |
| | |
| | |
+---------------------------+------------+
| echo area |
+----------------------------------------+
As you import data into Athena, data groups are created and those
groups are listed in the section labeled ‘Group List’ . You select a
group as the active one by clicking the left mouse button on its entry
in the group list. When selected, the list entry is highlighted with
an orange background and the parameters associated with that group are
displayed in the large area on the left labeled ‘Group Parameters’.
When you pass the mouse over a label in the group parameters section,
you will notice that the label changes color. This indicates that a
mouse click on the label will have an effect. Clicking the left mouse
button will display a hint in the echo area as to the function of that
parameter. See the section on group operations for the effect of a
right mouse click.
The view of the group parameters is replaced when certain features of
Athena are used. Choosuing any of the options from the Data, Align,
Diff, or Analysis menus will temporarily replace the group parameters
with views of parameters relevant to the chosen task. For example,
when the log-ratio option is chosen from the Analysis menu, the view of
group parameters is replaced by a view of the interface to Athena’s
log-ratio/phase-difference analysis.
Below the group list are two rows of button for plotting data. The red
buttons are for plotting the selected data group. The purple buttons
are for plotting multiple data groups. These buttons are labeled
according to the data space of the plot. E, k, R, and q refer to
energy, photoelectron k, real space R, and backtransform k,
respectively.
Below the plot buttons are a set of tabs for specifying the details of
the plots in each space. For each space you can specify the range of
the x-axis. For energy plots, you can select whether the background
function is plotted along with the data and whether the data and
background are normalized. For k-space plots, you can select the
amount of k-weighting. For R- and q-space plots, you can select which
part of those complex functions are plotted. There are also tabs for
setting up stacked plots and for establishing plot indicators. For a
complete discussion see the section on plotting.
Finally, at the bottom of the page is the echo area. Athena uses this
area to display hints, brief help messages, warnings, and updates about
recently performed analysis or plotting actions. A few features of
Athena will prompt the user for a text string. In those situations,
the echo area is temporarily replaced by text string dialog.
Throughout Athena the right mouse button serves to post context
sensitive menus. These include parameter labels, groups list entries,
and other elements on the screen. You should try clicking the right
mouse button in different places to see what usefuls things might pop
up.
REFERENCES
Here are the relevant URLs:
IFEFFIT
http://cars.uchicago.edu/ifeffit
PGPLOT
http://www.astro.caltech.edu/~tjp/pgplot/
Perl
http://www.perl.com
perl/Tk
http://www.lehigh.edu/~sol0/ptk/
Central atom phase shifts
http://leonardo.phys.washington.edu/~ravel/software/feff_tables/
MISSING FEATURES
You betcha! Lots! Here’s a partial list:
* Principal Component Analysis on the set of marked groups
* XANES analysis by fitting a sum of scans to an unknown
* Dead-time and self-absorption corrections
* Handle dispersive data sets, i.e. data sets wherein the I0 and IT
measurements are in separate data files becuase the data were
obtained sequentially
* Calibrate dispersive data to a trusted standard
* Handle SPEC files. An independent perl module would be ideal. This
is a project some eager contributor could tackle without having to
delve into ATHENA’s source code.
* Alignment of scans using a reference, either of the same edge or of
a nearby edge. (Any suggestions? I am lacking a good idea about how
to implement this...)
* Formulas for the energy axis (useful for converting encoder
readings to energy values)
* R and q space records, that is to be able to read and write data in
R and q space just as easily as E or k space.
* Internationalization. That is, build a framework for having text
strings read from external files and for the language to be a
configuration option.
* Documentation, documentation, documentation
WHAT’S IN A NAME?
Athena was the goddess of wisdom and is also associated with skill and
justice. Those are all good qualities for a data analysis program!
OPTIONS
This program requires no options.
SEE ALSO
This program is part of the horae XAS analysis suite which can be
obtained at
http://cars9.uchicago.edu/~ravel/software/
AUTHOR
Bruce Ravel <ravel@phys.washington.edu> (c) 2001 - 2003
Ifeffit is copyright (c) 1992 - 2003 Matt Newville
newville@cars.uchicago.edu
http://cars9.uchicago.edu/~newville/ifeffit/
June 26, 2006 athena(1)