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.

   3. SingleMap mode – Press the Select Jump-Ratio Map button

   4. MultiMap mode – Specify via the MultiMap Configuration dialog

   5. 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