Periodic Reporting for period 4 - HDEM (High Definition Electron Microscopy: Greater clarity via multidimensionality)
Reporting period: 2023-09-01 to 2024-12-31
The high definition electron microscopy (HDEM) project has enhanced the definition at which the atomic structure of materials can be seen. This is important as the properties of materials are determined by their atomic structure and understanding the correlation between structure and properties is crucial to advancing our fundamental understand of materials which is vital for both technological advance and many applications in biology and medicine.
For many materials substantial challenges to seeing their atomic structure are imposed by their susceptibility to damage by electron beams. We have addressed this by developing sophisticated techniques that are able to extract more information more efficiently. To do so, we have harnessed technological developments such as event driven 4D scanning transmission electron microscopy (STEM) and electron ptychography. These bring not only greater dose efficiency but greater sensitivity, allowing us to better reveal light elements and even detect changes in charge density due to bonding involving the transfer of single electrons between atoms.
The methods we have developed enable us to better understand materials ranging from organic perovskite solar cells in green energy and materials science and physics to biological materials such as proteins, and thus facilitate advances in society ranging from technology to medicine.
For many materials substantial challenges to seeing their atomic structure are imposed by their susceptibility to damage by electron beams. We have addressed this by developing sophisticated techniques that are able to extract more information more efficiently. To do so, we have harnessed technological developments such as event driven 4D scanning transmission electron microscopy (STEM) and electron ptychography. These bring not only greater dose efficiency but greater sensitivity, allowing us to better reveal light elements and even detect changes in charge density due to bonding involving the transfer of single electrons between atoms.
The methods we have developed enable us to better understand materials ranging from organic perovskite solar cells in green energy and materials science and physics to biological materials such as proteins, and thus facilitate advances in society ranging from technology to medicine.
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.
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.
Our work has taken electron microscopy well beyond the state of the art. We have removed the barriers to performing 4D STEM high speed facilitating drift free low dose ptychography than can be acquired simultaneously with the analytical Z-contrast signal. Our methodological developments enable us to remove artefacts in ptychography images from both residual aberrations and contrast reversals, and provide proper quantification of the complex phase images. Applying these developments we have demonstrated the ability to detect the effect of bonding with direct imaging at the full resolution of the microscope, including at defects. Our work has demonstrated significant advantages for 3D imaging and single particle analysis with ptychography. We have also achieved the lowest dose atomic resolution imaging with ptychography to date, providing detailed information that was previously impossible to obtain.