Jump-Ratio Map

Two techniques are commonly used in EFTEM to map elemental distribution: 2-window ratio mapping and 3-window elemental mapping. The jump-ratio approach requires two energy-filtered images, one you position just before the ionization edge (pre-edge) and one just after the edge (post-edge). In the jump-ratio approach, the post-edge image is divided by the corresponding pre-edge image to produce a map that indicates the distribution of the element you select.

1. To acquire a jump-ratio map, specify:
   1. Element of interest
   2. Camera parameters
   3. Slit width and filter energies to be used for the pre- and post-edge acquisitions

2. Access the Configure Jump Ratio dialog will vary based on your chosen mode.
   1. SingleMap – Press the Select Jump-Ratio Map button
   2. MultiMap – Specify via the MultiMap Configuration dialog
   3. Indicate parameters within the Configure Jump Ratio dialog
      1. Window settings (eV)
         1. Setup – Allows you to recall pre-saved or default settings for a particular element
         2. Slit width – Specify the energy-selecting slit width you want to use for both the pre- and post-edge acquisitions
         3. Post-edge – Designate the energy loss setting that the filter will use to acquire the post-edge image
         4. Pre-edge – Indicate the energy loss setting that the filter will use to acquire the pre-edge image
         5. Edge – Specify the edge you want to use for ratio mapping
      2. Detector – Specify the detector settings you want to use
      3. Spectrum display – Generates and displays a simulated spectrum at the top of the dialog to give you visual feedback regarding the feature shape and the selected acquisition window positions
3. Click Capture.

The routine will

• Acquire the post-edge image followed by the post-edge image.
• Correct for any spatial drift between the images.
• Compute and display the ratio map.

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