MRI: Acquisition of a Direct Detection Electron Camera for an Existing Scanning Transmission Electron Microscope for Low-Dose and Phase-Sensitive Imaging of Materials

Non-Technical Description:

The purpose of this major research instrumentation project is to acquire a direct electron detection camera for a transmission electron microscope at the University of Oregon. The shared-use electron microscopy facility in the Center for Advanced Materials Characterization in Oregon (CAMCOR) serves as a regional resource for researchers interested in analyzing the structure and properties of a variety of natural and engineered materials and devices.

Electron microscopy is an important tool for imaging and measuring the atomic structure and composition of materials, but some materials are quickly damaged by exposure to an electron beam. Furthermore, many structures and processes are difficult to image using conventional cameras because of low contrast. The higher efficiency and speed of this new camera delivers large improvements in image detail and contrast, enabling imaging of dose-sensitive samples and providing videos of fast processes at the nanometer scale, all of which are important to the characterization of advanced materials.

As part of an existing infrastructure supporting numerous outreach and educational opportunities, the direct electron detector is also used for an array of curriculum and professional development opportunities for users across age, disciplines, and academic stages across the Northwest. Undergraduate, graduate, and postdoctoral researchers obtain hands-on experience learning transferrable skills in electron microscope operation and analysis, and in the generation, handling, and processing of large image datasets.

This detector strengthens an existing summer research course designed to engage undergraduates in nanoscience and physics research. Technical Description:

The native ability of the direct electron detector to record high-resolution electron images at rapid speeds is applied to observations of low-contrast dynamic processes, such as oxidation catalysis in a liquid cell sample holder for a transmission electron microscope, the evolving cathode material structure throughout charge/discharge cycles in lithium-ion batteries, and crystallization kinetics of materials at the nanoscale. The high detection efficiency of the new detector is also used to develop electron interferometry techniques.

Electrons in a coherent superposition of paths combine to form an interference pattern, providing enhanced sensitivity to specimens. The detector's ability to record single-electron events at the output of an electron interferometer enables quantum-inspired measurement protocols such as interaction-free measurements and enhanced phase imaging. In this way, the direct electron detector provides researchers with a greater opportunity to study and understand a wider variety of material systems and processes as well as to perform quantum mechanical experiments.

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.