Two high-resolution microscopes will allow researchers to study and test materials at the atomic level with unprecedented precision. Standing beneath a pearly white, towering microscope called the JEOL NEOARM, Penn's Douglas Yates explains that scanning transmission electron microscopes are so powerful they can image down to the atomic level.
These microscopes fire energetic electrons through the object being examined. This allows researchers to create an atomic-scale image through the interaction between the electrons and the atoms in the sample.
This instrument is unique because it reaches the sub-angstrom level, down to 78 picometers,” says Yates, director of the Nanoscale Characterization Facility in Penn’s Singh Center for Nanotechnology. “We’re now in the sub-nanometer realm.
Scientists at the Singh Center can now use two of these advanced microscopes: the NEOARM and another called the F200. The F200 will be used for most material analyses, while the NEOARM will be used for viewing objects at the highest possible magnification at a low electron voltage.
The microscopes will support research, including projects funded by the National Science Foundation’s Materials Research Science and Engineering Centers program, which is headquartered at Penn’s Laboratory for Research on the Structure of Matter.
He describes how to prepare the system to analyze the sample to Nicole Bohn, a senior from Enola, Pa., and science, technology, and society major. Bohn, who’s also pursuing a minor in materials science and engineering, trains researchers on how to use traditional scanning electron microscopes.
The electron gun generates a beam of electrons, which is projected onto a thin sample. The interaction of the electrons with the atomic structure of the sample generates an image, which is magnified and projected onto a fluorescent screen or camera.
These microscopes provide record resolution at low-electron voltages, and therefore minimal sample damage. Minimal damage is key when analyzing 2-D materials like graphene. Low-voltage electrons allow researchers to control their sampling, while high-voltage electrons would knock atoms out of place.
Some nanotech research projects at Penn require to pinpoint precision for creating purposeful notches or holes in a material to understand how “defects” can be beneficial, so low-electron imaging is crucial.
There is still much to be understood about how to best exploit this new capability for soft matter. Erich Stach, professor in the Department of Materials Science and Engineering Traditional electron microscopes require upward of 300 kiloelectronvolts (KeV) to produce high-resolution images.
Thanks to the scanning electron microscopes, that’s no longer a problem. The NEOARM requires just 30 KeV for high-quality resolution. JEOL, the manufacturer of the F200 and NEOARM, teamed up with Penn partly because it brings their newest technology to a wide audience. JEOL representatives attended a symposium at the Singh Center.
Penn has been home to JEOL microscopes for more than 40 years. We’re excited to expand upon this relationship and push the boundaries of nanotechnology. It is an honor to have these world-class instruments in the hands of world-class researchers at a peerless university like Penn.