The Universe is my nano-fab: scanning transmission electron microscopy of carbonaceous nanomaterials

Rhonda Stroud, Naval Research Laboratory


Although nanoscience is a relatively new field of study, nanomaterials have existed for billions of years.  Technologically important materials, such as graphene, nanodiamond, and SiC formed first not in clean-room fabrication facilities, but in the outflows of ancient dying stars.  In the laboratory, the atomic-scale ordering, impurity and defect content of these materials can be optimized by manipulating the thermodynamic and kinetic growth conditions for specific optical, electrical or other properties. A better biocompatible quantum dot, for example, comes from careful incorporation of N or Si impurity atoms into nanodiamond.  In space, the same thermodynamics and kinetics apply; the atomic-scale structure is a function of pressure, temperature, etc.. But in this case the impurities are fortuitously incorporated, and serve as a witness to the presolar origin rather than a commercial purpose. Aberration-corrected scanning transmission electron microscopy (AC-STEM) can reveal the structure of carbonaceous nanomaterials, often down to the individual impurity atom, whether from the lab or space.  This talk will cover examples of the state-of-the-art in AC-STEM from both the natural and synthetic worlds of carbonaceous nanomaterials.

Dr. Rhonda Stroud is the Head of the Nanoscale Materials Section of the Materials Science and Technology Division of the Naval Research Laboratory in Washington, DC, where she oversees the DoD’s most advanced electron microscope facility for nanoscale materials characterization. Her research interests span many classes of materials, from quasicrystals and oxide electronics to aerogel nanocomposites and nanoparticles formed in supernovae.  She received her B.A. in physics from Cornell University in 1991, and her Ph.D. in physics from Washington University in St. Louis in 1996.  She is a Fellow of the American Physical Society and the Meteoritical Society, and is currently the President of the Microanalysis Society of America.