Manipulating Spectra
is a common EDS spectral artifact that occurs exactly one Si K x-ray energy (1.74 keV) below sufficiently energetic x-rays. Special peaks. Te KLM tree view allows you to select
characteristic transitions, absorption edges, and silicon escape peaks. Te tree view interface allows you to select groups of lines quickly yet also permits selecting or deselecting individual lines. Transitions are subdivided into major lines and minor lines to mitigate line clutter. Furthermore, if the cursor is located in the element edit box, keyboard shortcuts can be used to select sets of lines. “Alt-K,” “Alt-L,” and “Alt-M” select the K, L, and M families, respectively. “Alt-S” selects Si escape peaks, and “Alt-E” selects absorption edges. Using the mouse wheel and the keyboard, it is easy to label spectra with many elements. One additional type of marker line is supported
by DTSA-II: coincidence (sum) peak labels. Once the major elements in a spectrum have been identified and the characteristic lines labeled, DTSA-II can assist with identifying likely coincidence (sum) peaks. Selecting a narrow region of energies bounding the center of the unlabeled peak and then right-clicking over the yellow highlighted region will bring up a menu. Selecting the “ID sum peak” menu item will search through the list of selected major transitions for combinations whose sum falls within the selected energy window. Te line will be labeled with the name of the transitions concatenated with a “+” sign or when the sum results from two photons from a single transition “2 ×” the name of the transition.
Publication Quality Output Generating publication-quality output of x-ray spectra
can be tedious with generic plotting soſtware. In addition to the challenges of importing x-ray spectra data files, there are additional challenges related to labeling and scaling KLM markers, absorption edges, and escape peaks. DTSA-II provides two alternatives to save the current spectrum display in formats suitable for publication. Te spectrum display window’s main menu contains a “save” submenu. Tis submenu contains menu items to save the spectrum “as displayed” or “as a gnuPlot script.” Te “as displayed” option allows you to save the spectrum display in its current configuration as a Scalable
Vector Graphics (SVG), JPEG, PNG, TIFF, or Windows Bitmap (BMP) file. Select the format using the “file type” selector on the “Save as” dialog box. Te resolution of this output is 4 times higher than that displayed on the screen while retaining the same aspect ratio. Fonts are also slightly upscaled to be more appropriate for publication. Te SVG format is a vector- based format, which means it can be scaled almost infinitely without pixelation. Te SVG format can be edited using Adobe Illustrator [4], Corel Draw, or the open-source application InkScape [5], allowing additional labels to be added. Te result from one of these programs can then be exported in a wide array of formats. Te “save” → “as a gnuplot script” option outputs a script compatible with the open-source plotting package gnuplot [6]. Gnuplot is a flexible (albeit hard-to-use) package for generating publication-quality graphics in various formats including encapsulated Postscript (EPS) and LaTeX. DTSA-II will generate a starter script containing the spectral and marker line data, which can then be customized with a text editor.
References [1] NWM Ritchie, Microscopy Today 19(1) (2011) 26–31. [2] EMSA format: ISO 22029:2003 or
http://www.amc.anl. gov/ANLSoſtwareLibrary/EMMPDL(old)/Xeds/EMMFF/
emmff.doc.
[3] International Union of Pure and Applied Chemistry, “Nomenclature, symbols, units and their usage in spectro- chemical analysis—VIII. Nomenclature system for X-ray spectroscopy (Recommendations 1991).” See Section 3.
http://old.iupac.org/publications/analytical_compendium/ Cha10sec348.pdf
[4] Disclaimer: Certain commercial equipment, instru- ments, or materials are identified in this article to foster understanding. Such identification does not imply recommendation or endorsement by the National Institute of Standards and Technology, nor does it imply that the materials or equipment identified are necessarily the best available for the purpose.
[5]
http://inkscape.org/ [6]
http://www.gnuplot.info/
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