Dr. Philipp Heck, the Robert A. Pritzker Associate Curator for Meteoritics and Polar Studies and head of the Robert A. Pritzker Center, published a paper on atom-probe tomography of nanodiamonds from The Field Museum’s Allende meteorite in the journal Meteoritics & Planetary Science. This is the first application of the novel technique of Atom-Probe Tomography (APT) in the field of cosmochemistry. Some of these nanodiamonds are presolar—that is, older than our solar system—and haven’t changed since they formed more than 4.6 billion years ago. These grains are almost entirely made out of carbon, the most important element for life on Earth, and represent the tiny fraction of material that survived the formation of the solar system. Philipp is interested in studying their presolar stellar origins, which is only possible with APT. First the diamonds had to be prepared for analysis, an extremely difficult task because of their small size of only 2 to 3 nanometers in diameter. Since 2009 Philipp has lead an interdisciplinary team of scientists from cosmochemistry, materials science, physics, and chemistry to develop sample preparation methods and analytical protocols to analyze individual nanodiamonds with APT. After several years of hard work Philipp and his team of collaborators finally succeeded with their analyses. The image here shows an atom-by-atom tomographic reconstruction of a tip-shaped sample containing meteoritic nanodiamonds (the grey- shaded areas); each dot in the image is an individual atom. This approach opens up new avenues for analyzing nanoparticles from extraterrestrial (and terrestrial) rocks, and will also help to answer the question of the origin of the nanodiamonds, important carriers of presolar carbon. The paper can be accessed online at this link.
The project was funded with support from the Tawani Foundation and NASA, and the instruments and tools used were funded by the US Department of Energy, the National Science Foundation and the Office of Naval Research.