## EXODUS

Note that the EXODUS module is a general XOP utility and has a help page from XOP.

However, it has some additional functionality for XAFS, and these items are activated when starting EXODUS from XAID.

In this help page, only the XAFS particularities are treated.

## Module characteristics

- Goal: to load a SPEC file, or multiple ASCII files, and selecting, viewing, averaging, and perform operations with data from multiple scans.
- Input: A SPEC file, an individual or multiple ASCII multicolumn files
- Output: The data contained in EXODUS can be exported to other programs, including XAID applications, or exported to files in several formats.
- Tricks:
  - Multiple selection: for exploiting all the possibilities of EXODUS, it is essential to know how to select multiple lines in the lists. Click on a line for a single line selection. Then press Shift and click on another line on the same window (while Shift is pressed) for selecting a block of lines. For selecting multiple individual lines use Control instead of Shift.

## Example of Use

1. Start EXODUS from the main XAID window
2. Load Data by either

1. Import a SPEC file The list of scans appears in the left window.
   Copy from left (import) window to right (process) window the data to be processed
2. Import multiple ASCII files. For instance using:
   and selecting trhe Gezeo*.* files in the xaid/Examples directory:
   As a result, the different data files are loaded into EXODUS, which shows multiple data lines:
3. Select the first line, and Export: XAID/Mu2Chi. A new XAID_MU2CHI window will appear. Enter the needed conversion factor to go from keV to eV (and "Enter") : . Then click for getting the EXAFS signal:
   Then, in the XAID_MU2CHI window, open File->Preferences... and set:
   Now, XAID_MU2CHI is prepared to receive multiple data sets.
4. Without quitting XAID_MU2CHI, go to the EXODUS window and perform a multiple selection:
   and Export: XAID/Mu2Chi. You will see new lines appearing in the EXODUS window, containing the EXAFS signals of the input lines, as calculated by XAID_MU2CHI:
5. Without deselecting them, Export: XAID/ff. The Fourier Transforms of the signals are calculated, and the outputs are sent to new lines in the EXODUS window:
6. The selected data in EXODUS can be exported in several formats. For instance, Export: XPLOT/SPEC Mesh will create a 3D mesh with the corresponding Spec file (if wanted):
7. The Operations pulldown menu allows to average, interpolate and make calculations with data. Some operations are:

1. O perations:do on each set ->Interpolate This option builds interpolated or resampled data sets from the selected ones. The interpolated/resampled data sets will have the same abscissas array. The abscissas array can be selected between different options: i) like the first data set, ii) customized with constant step in Energy scale, and iii) customized with constant step in k scale. The results can be added to the list of data sets (right panel) or be injected in XPlot for visualizing in 2D (multiple column format) or in 3D.
   Two algorithms are available:
   i) I nterpolation: linear interpolation. The y value for the new x value is calculated by linear interpolation between the two closer neighbours. This option is recommended when the number of points of the interpolated array is of the order or bigger than the number of points of the original array.
   ii) R esample: Some kind of smooth interpolation. For each resampled point x[i] of xNew it calculates yNew consisting in the average y values of all points (x,y) sitting in the interval [x[i]-0.5*step1,x[i]+0.5*step2], with step1=x[i]-x[i-1] and step2=x[i+1]-x[i]. In the case that step1 or step2 are undefined (first and last points) we used step=[x[1]-x[0]] instead step1 or step2
2. Operations:->Interpolate and-> Average This option averages the selected data sets. For that, if the abscissas are different, it makes an interpolation (see before). The result is added to the list in the right panel.
3. O perations:->Interpolate and->Sum This option sums the selected data sets. For that, if the abscissas are different, it makes an interpolation (see before). The result is added to the list in the right panel.
4. O perations:->Interpolate and->Customized This option allows you to program a customized operation. The result is added to the list in the right panel.
5. O perations:->Interpolate and->Fit LinCom This option allows you to perform fit a given data set in the list (target) as a linear combination of other data sets (components) in the list. This option is useful whilst analyzing XANES spectra of compounds or mixtures, and wanted to know the percent of its components. The data sets to be used as target and components are identified by their indices in the right panel list, starting from zero. If the list is long, you may want to use the View:->Info option to help in identifying the indices of the wanted data sets. The fit is performed using the Levenberg-Marquardt [MINPACK-1] method as implemented in the MPFit IDL routine. The result of the fit is added to the right panel list.
6. Operations-One each set-> XANES normalization
7. Operations-Parameters from blocks. This option permits to extract a parameter from each selected data set. It is useful to calculate parameters from multiple spectra versus the spectra number: Examples:

1. For calculating the standard deviation of the spectra enter: out=(moment(y))[1]
2. For calculating the integral of the spectra enter: out=int_tabulated(x,y)