4. April 2019
Electron microscopy with DECTRIS QUADRO: Atomic resolution and ultra-high dynamic range
QUADRO, the first DECTRIS electron detector, is almost ready, and we’ve already seen very promising results. This detector has produced electron diffraction patterns with extremely high dynamic range, and it has also achieved atomic resolution images. In short: DECTRIS is going to make materials scientists very happy.
“In electron diffraction experiments, the direct beam is often blocked,” explains DECTRIS Product Engineer Dr. Luca Piazza. “Otherwise, the high intensity of the flux would harm the sensor.” However, with the QUADRO detector, DECTRIS has been able to get an accurate count from both the unscattered beam and the weaker Bragg spots – without damaging the detector.
Figure 1: Molybdenum Disulfide monolayer diffraction pattern
With the new DECTRIS detector, the electron microscopy community will finally be able to enjoy the advantages of hybrid photon counting (HPC) technology. Direct electron counting and the demonstrated ultra-high dynamic range are just two examples of the technology’s benefits. Another feature of DECTRIS’ detectors is speed: direct detection matched with a parallel readout system creates images faster than traditional techniques do.
Having a detector that can take more than 2,000 pictures per second is surely useful for all applications, but in-situ electron microscopy is one obvious field that will benefit from these high speeds. Furthermore, DECTRIS detectors, including the new QUADRO, provide detective quantum efficiencies that are much higher than those of other detectors, allowing for reduced radiation damage. This means scientists can get more information out of their samples with fewer electrons.
Another EM application in which speed is particularly crucial is electron imaging. The DECTRIS electron microscopy test laboratory does not feature ideal conditions; it would never pass room check because of the thermal and electrical interference – not to mention the vibrations from the gym right behind the wall! Nonetheless, the DECTRIS QUADRO, mounted onto a Tecnai F20 TEM, achieved atomic resolution simply because it could snap a considerable number of images so fast that building instabilities could not interfere with the recording process.
Figure 2: Molybdenum Disulfide monolayer with atomic resolution
“This could be a game-changer,” summarizes Dr. Sacha De Carlo, DECTRIS Business Development Manager EM. “Imagine what a materials scientist could do with a standard 200 kV microscope equipped with our QUADRO.” On the other hand, if the lab is equipped with a top-of-the-line STEM, techniques like 4D-STEM and electron ptychography have a very bright future.
We acknowledge Dr. Thomas LaGrange of EPFL for providing us with the Molybdenum Disulfide samples.