Extended Data Fig. 8: Effect of chromatic aberrations at different electron doses for ptychographic reconstructions of monolayer MoS2 using simulated datasets at 80 keV. | Nature

Extended Data Fig. 8: Effect of chromatic aberrations at different electron doses for ptychographic reconstructions of monolayer MoS2 using simulated datasets at 80 keV.

From: Electron ptychography of 2D materials to deep sub-ångström resolution

Extended Data Fig. 8

Two convergence semi-angles are shown, 21.4 mrad (left two columns) and 35 mrad (right two columns), representing conditions under which chromatic aberrations have moderate and large effects on the incident probe shape, respectively (Cc = 1.72 mm, ΔE = 1.1 eV). 21.4 mrad is also the experimental convergence angle. The incident electron dose levels are an infinite dose (top row), the experimental dose of 1.16 × 105 electrons per Å2 (middle row) and a low dose of 104 electrons per Å2 (bottom row). In the presence of noise, chromatic aberrations degrade the phase range of the reconstruction compared with the achromatic data. The data for the larger convergence semi-angle are more strongly affected. At infinite and experimental doses, ptychographic reconstructions with and without chromatic aberration are visually similar for both convergence angles. At low dose and with chromatic aberration, the reconstructed atoms are broadened, and distinct artefacts appear for a convergence angle of 35 mrad.