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

C J R Duncan; M Kaemingk; W H Li; M B Andorf; A C Bartnik; A Galdi; M Gordon; C A Pennington; I V Bazarov; H J Zeng; F Liu; D Luo; A Sood; A M Lindenberg; M W Tate; D A Muller; J Thom-Levy; S M Gruner; J M Maxson

doi:10.1016/j.ultramic.2023.113771

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

Ultramicroscopy. 2023 Nov:253:113771. doi: 10.1016/j.ultramic.2023.113771. Epub 2023 Jun 5.

Authors

C J R Duncan¹, M Kaemingk², W H Li², M B Andorf², A C Bartnik², A Galdi², M Gordon², C A Pennington², I V Bazarov², H J Zeng³, F Liu³, D Luo⁴, A Sood⁵, A M Lindenberg⁶, M W Tate⁷, D A Muller⁸, J Thom-Levy⁹, S M Gruner¹⁰, J M Maxson¹¹

Affiliations

¹ Cornell Laboratory for Accelerator-Based Sciences and Education, Cornell University, Ithaca, NY 14850, USA. Electronic address: cjd257@cornell.edu.
² Cornell Laboratory for Accelerator-Based Sciences and Education, Cornell University, Ithaca, NY 14850, USA.
³ Department of Chemistry, Stanford University, Stanford, CA 94305, USA.
⁴ SLAC National Accelerator Laboratory, Menlo Park, CA 94205, USA.
⁵ Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, NJ 08540, USA; Princeton Materials Institute, Princeton University, Princeton, NJ 08540, USA.
⁶ Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305, USA.
⁷ Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, NY 14853, USA.
⁸ Kavli Institute at Cornell for Nanoscale Science, Ithaca, NY 14853, USA; School of Applied and Engineering Physics, Cornell University, Ithaca, NY 14853, USA.
⁹ Laboratory for Elementary-Particle Physics, Cornell University, Ithaca, NY 14853, USA.
¹⁰ Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, NY 14853, USA; Kavli Institute at Cornell for Nanoscale Science, Ithaca, NY 14853, USA.
¹¹ Cornell Laboratory for Accelerator-Based Sciences and Education, Cornell University, Ithaca, NY 14850, USA. Electronic address: jmm586@cornell.edu.

PMID: 37301082
DOI: 10.1016/j.ultramic.2023.113771

Abstract

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.

Keywords: Direct electron detector; Moiré heterobilayer; Ultrafast science.