MicroscopyInnovations
Avoiding peak overlaps can be important in both quali-
tative and quantitative X-ray spectrometry. As an example, the use of copper grids must certainly be avoided in the case of a microcircuit with Cu interconnects, high-temper- ature semiconductor cuprates, or other copper-oxides. Te grid material may also emit X-rays that could overlap with X-rays from elements in the specimen. For a Cu grid, likely interferences are between Cu Kα and either Hf Lα or Ta Lα. Similar overlap issues would be observed with Mo, Ni, and other high-Z grids. Te high-temperature stability of the grids for specimen heating experiments is also important. It is known that in the absence of oxygen, diamond does not alter its composition up to 1000°C. At that high tempera- ture, the diamond material gradually transforms to graph- ite, still preserving its carbon-only composition.
Stela™ Hybrid-Pixel Camera Gatan, Inc.
Developers: Anahita Pakzad, Luca Piazza, Christoph Hoermann, Vittorio Boccone, Paul Mooney, Tom Sha, Mike Petrillo, and Bert Taube
Stela™ is a hybrid-pixel electron detector
fully integrated with the Gatan Microscopy Suite (GMS) soſtware for advanced electron dif- fraction studies. Stela uses the DECTRIS ELA hybrid-pixel electron detector that employs electron counting to minimize noise and uses on-the-fly digitization. Te high dynamic range attained allows the capture of both weak and intense reflections typical of advanced dif- fraction studies. DECTRIS hybrid-pixel tech- nology provides best-in-class performance in terms of detector noise, frame rate, point spread
function, and pixel dynamic range. Stela has been optimized for imaging at low kV, making it ideal for materials that require diffraction studies at <80 kV. At its fast frame rate, the system acquires hardware-synchronized 4D STEM datasets at >16,000 pixels/s. Tis fast frame rate means the operator can cover a large area of the specimen quickly while reducing specimen driſt and damage. Hardware-synchronized 4D STEM elimi- nates data loss during acquisition. Pre-optimized 4D STEM tools along with Python scripting allow for high-quality data acquisition and processing. Tus, Stela provides visualization and analysis of the 4D data stream, giving the scientist quick and efficient feedback and experimental control. Te 4D STEM is the next big leap for electron micros-
copy. Te combination of both real and reciprocal space in a single dataset opens new opportunities for data analy- sis, extending real-space resolution to mapping crystallo- graphic changes at near-atomic scale and possibly enabling the development of novel analysis methods. However, there are significant barriers to realizing this potential. A
2021 September •
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successful 4D STEM experiment relies greatly on robust and easy-to-use soſtware for data acquisition and analysis, and data quality is mainly dictated by the detector used to collect the diffraction patterns. With the introduction of Stela’s camera, the DECTRIS high-dynamic-range high- speed hybrid-pixel counting detector is fully integrated into the Gatan Microscopy Suite workflow to enable main- stream adoption of advanced 4D STEM diffraction experi- ments in electron microscopy labs across the world. Te main application of the Stela camera integrated
with DigitalMicrograph is 4D STEM, which allows studies such as strain mapping, orientation mapping, differential phase-contrast imaging, and ptychography. Tese advanced methods are used in characterization of metals and alloys, ceramics, semiconductors, and 2D materials.
Multi-Model in situ Bulk Liquid-Electrochemistry Microscopy
Hummingbird Scientific Developers: Norman Salmon and Daan Hein Alsem Hummingbird Scientific’s Multi-
model in situ bulk liquid-electrochem- istry microscopy platform enables in situ high-magnification microscopy and spectroscopy across TEM, SEM, and X-ray microscopy of
liquid-elec- trochemical processes that match the
behavior of bulk electrochemistry. It achieves this while main- taining all the features of traditional in situ liquid cell micros- copy systems: nanometer-scale membranes that enclose a thin layer of liquid environment, control of liquid pressure and flow, temperature control from RT to liquid boiling point, electrical biasing, and energy-dispersive X-ray spectrometry (EDS) for elemental analysis. Te present innovation involves miniaturizing standard bulk reference and counter electrodes (RE and CE) and placing them in-line with the liquid flow to the specimen. Te working electrode (WE) is located on the chip inside the liquid cell for imaging of the electrochemical process of interest. Tis configuration overcomes issues asso- ciated with using quasi-REs and quasi-CEs on-chip, which in previous studies have led to unstable rest potentials and a lack of distinct data peaks. Tus, previous results have been challenging (if not impossible) to relate to the electrochemi- cal process they are supposed to represent. We have overcome these issues with a miniaturized three-electrode bulk liquid- electrochemical cell that is small enough to fit inside the small specimen space in high-magnification TEM, SEM, and X-ray microscopes. Traditional in situ high-magnification liquid-cell
microscopy systems do not incorporate realistic bulk elec- trodes and reference electrodes. Previous attempts at high- magnification in situ liquid-electrochemical cells employ
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