How do elevated pressures within in-situ TEM gas cells influence imaging quality?
Hummingbird Scientific has collaborated with George Hollyer, Eric Stach, and colleagues at the University of Pennsylvania and Brookhaven National Laboratory to demonstrate imaging and diffraction of supported nanostructures under high-pressure gas cell transmission electron microscopy (TEM) using a modified version of the Hummingbird Scientific TEM gas heating sample holder. Co nanoparticles (15-20 nm) and deposited Pt were characterized using TEM, scanning TEM (STEM) and selected area electron diffraction (SAED).
a) Cobalt particles in DF-STEM at 10 bar N2, b) PVD Pt in DF-STEM at 27.5 bar N2. c) Cobalt particles in SAED at 3 bar N2, d) PVD Pt in SAED at 13.8 bar N2, e) PVD Pt in SAED at 20.5 Copyright © 2025 Springer Nature Limited
Integrity of the high-pressure gas cell formed by microfabricated chips was demonstrated up to 90 bar in a high-vacuum pump station and diffraction and imaging quality were assessed in a Titan 80-300 Environmental TEM (ETEM) at the Center for Functional Nanomaterials. Resolution of ~1.5 nm was achieved using deposited Pt islands at a broad range of pressures up to 27.5 bar of N2 using dark-field (DF)-STEM. Useful SAED patterns with distinguishable rings were also obtained at 3 bar N2 for the Co nanoparticles and up to 20 bar for deposited Pt. Ultra-high purity gases are required to mitigate beam-induced contamination at high pressure, and long purge times at startup are recommended. The holder showed remarkable stability and achievable resolution, opening the door for characterization of heterogeneous catalysts at industrially-relevant pressures and inevitable combination with elevated temperatures.
Reference: George Hollyer, Dmitri Zakharov, Daan Hein Alsem, Calvin Parkin & Eric Stach, MRS Commun. 15, 898-905 (2025) DOI: 10.1557/s43579-025-00825-7
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