Achieving sub-0.5-Angstrom resolution ptychography in an uncorrected electron microscope

<p><strong>Abstract:</strong> Sub-angstrom resolution has long been limited to aberration-corrected electron microscopy, where it is a powerful tool for understanding the atomic structure and properties of matter.<span> </span><span>&nbsp;</span>Here, we demonstrate electron ptychography in an uncorrected scanning transmission electron microscope (STEM) with deep sub-angstrom spatial resolution down to 0.44 &Aring;ngstrom, exceeding the conventional resolution of aberration-corrected tools and rivaling their highest ptychographic resolutions. Our approach, which we demonstrate on twisted 2D materials in a widely-available commercial microscope, far surpasses prior ptychographic resolutions (1 to 5 &Aring;ngstroms) of uncorrected STEMs.&nbsp; We further show how geometric aberrations can create optimized, structured beams for dose-efficient electron ptychography. Our results demonstrate that expensive aberration correctors are no longer required for deep sub-angstrom resolution.</p>