We have developed electron microscopy methods that enable us to do more with every electron passing through the sample. Key to this was the development of event driven 4D STEM. This overcame the speed barrier to performing 4D STEM within the powerful existing STEM workflows with no loss of speed. This was crucial to facilitate both low dose and drift free ptychography that enables a simultaneous Z-contrast signal to be collected.
We also developed methods of overcoming artefacts that can hinder ptychography, including lens aberrations and contrast reversals, and a reliable method of quantifying the phases of atomic sites was devised. These advances were crucial to achieving the accuracy needed to detect charge transfer due to bonding as we have demonstrated in a 2D material, including at its defects. We also developed the use of ptychography for 3D imaging. Significant effort was devoted to maximizing the low dose performance of ptychography. This involved investigating the performance of different algorithms and their transfer of information as well as developing the use of ptychography in single particle analysis.
Our advances and methods have been disseminated via many scientific talks, including 17 invited talks, and over 20 publications in international peer reviewed journals and conference proceedings. We expect additional high impact papers to be published in the near future.