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XAS Tutorials XAS Data Exchange with ASCII Tables ASCII Data Transfer Transferring "foreign" data into PROCESS is best handled by starting with (eV, absorption) data in two-column ASCII text format. These data can be generated by saving a ".mu" file from SIXPack, creating a text table using the standalone program TABLE, or any other program that can generate a two-column tab-delimited file. The "absorption" data may be raw or normalized and may be transmission or fluorescence, but usually is already ratioed. The following will use the example of a Hg L3 normalized data file HB70F.mu saved from SIXPack after background subtraction and normalization. Before beginning the transfer, view the text file using WordPad or NotePad to identify the number of header lines prior to the start of the tab-delimited data. For .mu files generated in SIXPack, this number should be 3. Start the transfer process by running PROCESS without a filename: C:\dir>process An X-window opens and PROCESS informs the user that no file was read.
Pressing any key brings you to the main menu of PROCESS …
Press 6 to get to the file input/output menu, then press 4 to read formatted file. Then follow the set of responses below to read 2 array positions from the file, writing the first into array position 1 and the second into array position 4 …
As indicated, choose 3 lines of header to skip. Then the following responses choose not to ratio data (they are already ratioed), choose to update the k scale, and define the E0 value for this edge (see Table). A warning appears, but can be safely ignored.
You should choose not to update k-weighted EXAFS, after which you are back to the I/O menu. Press 5 to return to main menu, then 7 for utilities, then 8 for memory map. You should see data in array positions 1 and 4 as shown below …
For reasons that appear to be associated with a "bug" in PROCESS, you cannot use the data just loaded unless you fill array positions 5 and 9 with some data. The following procedure simply copies data from array position 4 to array positions 5 and 9 …
Then press any key, then press 1 again (to move memory contents), then move data in array position 4 to 9 …
Once these moves are made, the resulting memory map should look like this:
Pressing any key, then Enter returns you to the UTILITIES menu.
Pressing A gets you back to the main menu, from which you should press 6 for file input/output, then 1 from the FILES menu to write the resulting .AVE file …
Enter the filename for the .AVE file, after which you can either exit PROCESS or continue processing this new .AVE file. Follow the XAS Data Reduction protocol, with the single exception that, in the spline fitting, you must specify the element (Hg) and absorption edge (L3) since these were not input from the CALIBRATE.DAT file. scott@chem.uga.edu |
