Multi-scale time-resolved electron diffraction: A case study in moiré materials

Ultrafast-optical-pump — structural-probe measurements, including ultrafast electron and x-ray scattering, provide direct experimental access to the fundamental timescales of atomic motion, and are thus foundational techniques for studying matter out of equilibrium. High-performance detectors are ne...

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Published in:Ultramicroscopy 2023-11, Vol.253, p.113771-113771, Article 113771
Main Authors: Duncan, C.J.R., Kaemingk, M., Li, W.H., Andorf, M.B., Bartnik, A.C., Galdi, A., Gordon, M., Pennington, C.A., Bazarov, I.V., Zeng, H.J., Liu, F., Luo, D., Sood, A., Lindenberg, A.M., Tate, M.W., Muller, D.A., Thom-Levy, J., Gruner, S.M., Maxson, J.M.
Format: Article
Language:English
Subjects:
Direct electron detector
MATERIALS SCIENCE
Moire heterobilayer
Moiré heterobilayer
PARTICLE ACCELERATORS
Ultrafast science
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Summary:Ultrafast-optical-pump — structural-probe measurements, including ultrafast electron and x-ray scattering, provide direct experimental access to the fundamental timescales of atomic motion, and are thus foundational techniques for studying matter out of equilibrium. High-performance detectors are needed in scattering experiments to obtain maximum scientific value from every probe particle. We deploy a hybrid pixel array direct electron detector to perform ultrafast electron diffraction experiments on a WSe2/MoSe2 2D heterobilayer, resolving the weak features of diffuse scattering and moiré superlattice structure without saturating the zero order peak. Enabled by the detector’s high frame rate, we show that a chopping technique provides diffraction difference images with signal-to-noise at the shot noise limit. Finally, we demonstrate that a fast detector frame rate coupled with a high repetition rate probe can provide continuous time resolution from femtoseconds to seconds, enabling us to perform a scanning ultrafast electron diffraction experiment that maps thermal transport in WSe2/MoSe2 and resolves distinct diffusion mechanisms in space and time. •We perform ultrafast electron diffraction on a WSe2/MoSe2 heterobilayer•We denoise diffraction data with high frame rate direct electron detection•Diffraction data resolves a 10 nm periodicity moiré pattern•High dynamic range allows simultaneous measurement of atomic-scale Bragg peaks•Scanning micro-diffraction shows dynamics from angstrom to millimeter length scales
ISSN:0304-3991
1879-2723
DOI:10.1016/j.ultramic.2023.113771