Measuring and Managing Electron Dose


Figure 1: Images of the AXON Dose TEM holder. The tip includes two areas—a Faraday cup for collecting beam current and a through-hole that allows the beam to pass through the tip so that its area can be measured using the camera. The Dose holder is connected to a picoammeter to accurately measure small currents. A software-driven automated workflow correlates beam current and beam area across all microscope settings.


metadata associated with the images. AXON Dose also allows users to set limits on dose and dose rate so that critical thresh- olds are not exceeded. Finally, AXON Dose has tools that allow quantification of beam damage in samples. Observing changes


in a sample’s diffraction pattern is a common way to identify beam damage in crystalline materials. As shown in Figure 3, AXON Dose can be used to correlate this “spot fading” with the onset of beam damage.


Figure 2: TEM images with “heatmaps” showing the cumulative dose imparted at a sample site produced using the AXON Dose software. Colors and color gradi- ents can be adjusted by the user. Optional text overlays show the current dose rate, the maximum cumulative dose on the image, and the dose area. Translation or changes in magnification create local “hotspots” with higher dose accumulation.


2022 July • www.microscopy-today.com 23


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