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Molecular Foundry

HIGHLIGHTSImaging the electron charge density in monolayer MoS2 at the Ångstrom scale
July 22, 2023

Scientific Achievement

a) Experimental electric field map corresponding to a unit cell of MoS2. The color intensity indicates the magnitude and arrows indicate the direction of the electric field. b) Electrostatic potential and (c) charge density corresponding to (a) with red indicating net positive charge and blue indicating net negative charge. d-f) DFT simulations matching the experimental observations.

Foundry staff and users used 4D-STEM to determine the projected electron charge density in monolayer MoS2 and evaluate the contributions of core and valence electrons.

Significance and Impact

Directly imaging electron charge density could provide new insights into atomic bonding. This work demonstrates the ability to image such bonding; however, better electron microscopes are still needed to see the fine details.

Research Details

  • Monolayer 2H-MoS2 is used as a model system to investigate the contributions of both the core and valence electrons to the projected electron charge density derived from simultaneous ADF-STEM and 4D-STEM.
  • The results matched the electron charge density predicted by density functional theory (DFT) blurred with the electron microscope’s extended beam shape.
  • The work points to the need for better electron microscopes to directly image the fine sub-Angstrom details of atomic bonding.
Martis, J., Susarla, S., Rayabharam, A., Su, C., Paule, T., Pelz, P., Huff, C., Xu, X., Li, H-K, Jaikissoon, M., Chen, V., Pop, E., Saraswat, K., Zettl, A., Aluru, N.R., Ramesh, R., Ercius, P., Majumdar, A. Nat Commun 14, 4363 (2023). DOI: 10.1038/s41467-023-39304-9

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