# Module DELIA (Dispersive Exafs caLIbration and Analysis)

## Module characteristics

- Goal: To perform operations over a bunch of spectra. Operations: calibration the spectra, extraction of the XAFS signal and Fourier (and back-Fourier) filtering. This applications has been designed for the particular needs of the ESRF/ID24 beamline. The Dispersive XAFS and Turbo-XAS techniques generate a huge amount of XAFS spectra in few seconds or minutes. This module allows the user to visualize the spectra, calibrate them, extract the XAFS signal and perform Fourier and back-Fourier transforms simultaneously over all the spectra by simply point-and-click.
- Input: a file with raw data. The standard input file contains three columns with X,Mu and Index, all floats, written in binary format by a big endian system. The file size is then number_of_points*3*8 bits. Note that you can run DELIA in both little or big endian systems, but the file must be written by a big endian system (or also by a little endian system but swapping the byte ordering). To load a standard raw data file use the Browser... buttin in the "Raw" control panel.
  DELIA also accepts other ASCII input files (using the File menu:
  - ASCII RAW data: a multicolumn file containing at least three columns (more columns also accepted) with X,Mu and index. The index can be any value that identify the spectrum. Usually indices are 0,1,2..., but can be, for example, a temperature value, etc.
  - Mu(E): a multicolumn file containing in the first column the Energy values in eV, and then one additional column for each spectrum (Mu(Energy)) value. When this kind of file is used, the interpolation and calibration analyses are skipped.
  - Mu(E): a multicolumn file containing in the first column the Chi values in A, and then one additional column for each spectrum (Chi(k)) value. When this kind of file is used, the interpolation, calibration, and extraction analyses are skipped.
- Output: The results of the operations performed with DELIA can be saved in either multicolumn ASCII data files or in sequential ASCII data files. They are usually saved from an XPlot window using the menu File->Write ASCII file with current set....
- Tricks:
  - Better use binary raw input files: they are smaller and load quicker.

## Follow the steps

The DELIA analysis is done in four main steps, Each step is implemented in a different panel in the main window: Raw, mu(E), chi(k) and Fourier. You should pass from one panel to the next one after completing the operations in the current one. The names are self explanatory:

1. Phase I [Raw]: allows to read raw data, visualize the individual spectra, overplot them. The user must identify the columns with X, Mu and indices. Using the ASCII raw sample file f29 I obtained the sample window 1.
2. Phase II [mu(E)]: Interpolation and Calibration. It allows the user to input the parameters. Default parameters for the interpolation limits are presented. The minimum correspond to maximum value between all the abscissas spectra minima, and the maximum corresponds to the minimum between all abscissas maxima. They may be changed by the user. The user should also supply the calibrating coefficients a,b,c. By using the Get... button, the XAID_CALIB application is started to help in finding the coefficients. The coefficients found in this way are automatically transferred to the DELIA window. Once all parameters are filled, predd the RUN interpolate & calibrate button to make calculations over all spectra. The results appear in the "Result:" text window and also in a newly created XPlot window. The results can be visualized using the 2D and 3D buttons.
   If you want to create a file for further use with DELIA, press the 2D button, and from the XPLot window, select File->Write ASCII file with current set..., select then Data to save: All columns and Include header (SPEC type): No. The resulting file can then be loaded using the DELIA File->Load file with Mu(E)... menu. Some example windows are in windows 2 and 3.
3. Phase III [chi(k)]: extraction of the XAFS signal, i.e., calculate Chi(k) from Mu(Energy) over all the spectra. For selecting the appropriate parameters for the extraction, the user must perform interactively the extraction on a single spectrum (select its index and then press the Go button to start XAID_MU2CHI module (remember to perform the extraction in k space). The parameters of the extraction are copied automatically to their respective boxes. The results can be visualized in 2D or 3D and saved to a file for further use in DELIA as shown in Phase II. See examples in windows 4 and 5.
4. Phase IV [Fourier]: Fourier transform and filtering. As in the previous phase, the user must first perform the Fourier Filtering on a single Chi(k) spectrum, by using the XAID_FF module. The parameters are copied automatically. A sample can be found in window 6 and

## FAQs

- What to do if the programs crashes?
  Restart from scratch.

## Window examples

Window 1. Main panel after loading the ASCII raw data file f29.

Window 2. Main panel after interpolation and calibration (Phase II).

Window 3. XPlot window after interpolation and calibration (Phase II).
(Click on the image for full resolution.)

Window 4. Main DELIA window during XAFS extraction (Phase III).

Window 5. XPlot window after XAFS extraction (Phase III).
(Click on the image for full resolution.)

Window 5. Main DELIA window during Fourier Filtering (Phase IV).

## Acknowledgement

Thanks to the ID24 staff for providing me with the example data.

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