Pushing the limits of transmission electron microscopy of polymers

Project: Research project

Project Details

Description

PART 1: NON-TECHNICAL SUMMARY

Microscopic visualization at the atomic and molecular scale is transforming the understanding of how organic and inorganic materials organize and function. The tremendous advances in electron microscopy instrumentation continue to push the limits of what is possible, even with biological and organic compounds that are inherently susceptible to degradation from exposure to electron beams. Nevertheless, many of the recent advances are not tailored for microscopy of polymers. This project will develop electron microscopy tools to characterize the structure of conducting polymers in new ways and push the limits of imaging at the molecular or atomic scale. These techniques will not only advance the fundamental science of how the chemical structure of polymers impacts the microstructure but also how chemistry affects macroscopic properties. The emphasis on conjugated polymers will accelerate the development of flexible electronics and bioelectronics and thereby benefit society by impacting energy harvesting and health. Furthermore, integrated educational and research activities will deliver a carefully tailored message to first year undergraduate students of how engineering can help society, as an effort to enhance recruitment and retention of students from underrepresented groups. The investigator and graduate students involved in this project will further support diversity in engineering by offering mentorship and research experiences to undergraduate students.

PART 2: TECHNICAL SUMMARY

The planned research is centered on pushing the limits of polymer electron microscopy. Recent work has demonstrated the importance of secondary events on radiation sensitivity, and these new concepts suggest new approaches to mitigate damage and thereby push the resolution limit. An emphasis of the proposed work is on demonstrating the consequences of advances of detectors on polymer microscopy, including pixelated scanning transmission electron microscopy (STEM) detectors and direct electron detectors. Resolving diffraction spots with a focused probe allows for 4D STEM, and therefore mapping of pi-pi stacking in a manner not otherwise possible. In combination with auto-samplers, 4D STEM will allow of mapping of conductive pathways over large distances. The enhanced signal-to-noise ratio of direct electron detectors enhances the sensitivity of energy-filtered TEM to differences in elemental composition, or when used in the low-loss regime, to differences in valence electronic structure. Combining energy-filtered TEM with electron tomography will rely on such detector advances, to minimize the dose required for acquisition. Furthermore, the automatic acquisition of thousands of images that can then be averaged to enhance the signal-to-noise of lattice planes, or even reconstruct the unit lattice, would push the resolution limit of polymer electron microscopy beyond the Glaeser equation for radiation damage.

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This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

StatusActive
Effective start/end date6/1/195/31/23

Funding

  • National Science Foundation: $560,000.00

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