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Double Atan EELS Background
Function
Creates a stepped continuum function under EELS white lines, using a double arctangent function. This is a simple empirical model of the continuum and can be used for extracting white line intensities for valence state determination. The dialog-based script allows rapid interactive fitting of the acrtan function to EELS spectra.
Version
version:20150402, v2.0
Author
D. R. G. Mitchell
Acknowledgements

This approach is described in P. A. van Aken et al., Phys. Chem. Minerals, 29 (2002 ) p188-200.

Comments

van Aken et al. have tested this approach against the peak integral method normally used for valence state determination and have found it to be superior.

The script works on the front-most image which must be a spectrum. The fit is optimised when the 'Get EELS' button is pressed. 'Measure' will compute the white line intensities and various ratios. The position of the white lines peaks may need manual refinement as may the h1 and h2 values - the minima after the first and second peaks respectively. The magnitude of the +/- step sizes can be changed with SHIFT, ALT and CONTROL or values entered directly.

Default values and some hidden settings are saved in the Global Info tags under EELS Tools/Double Atan Background.

Updated in v2.0. Now includes automatic double atan background fitting to the front-most spectrum. The spectrum should be a background subtracted transition metal white line EELS spectrum. The automatic fit can be manually refined if necessary. Braching ratio is now reported in the dialog as well as in the output window.

System Requirements
Tested on GMS 1.8.x and GMS 2.x .
Known Issues
-
Supported
Yes.
Included Files
Script file.
Source Code
See attached script file.