Our Earth is a rocky planet largely composed of quartz, olivine, and a few other minerals. The greatest atomic contributor to these minerals and to the Earth itself is oxygen followed by notable amounts of silicon, magnesium, iron, and some aluminum. However, before these atoms can form rocks which form planets, they likely must first form small molecules which can form nanocrystals and then rocks. This class of small, inorganic molecules has largely been unexplored in the chemical literature. This CCSD(T)-F12/cc-pVTZ-F12 and MP2/6-31+G* quantum chemical study analyses monomers, dimers, and trimers of the minerals enstatite (MgSiO3), forsterite (Mg2SiO4), and spinel (MgAl2O4), combinations of either silicon dioxide or aluminum (III) oxide with magnesium oxides. Most notably, each of these molecules have very strong absorption/emission features beyond 9 microns where there exist very sharp IR lines in reference astronomical IR spectra. This is due to the large electronegativity gradient in the constituent atoms. Hence, these or related molecules may help to explain portions of unattributed IR spectra as well as provide evidence for the early stages of nanocrystal formation in protoplanetary disks leading to planet formation. Conversely, the presence of these molecules in planetary nebulae, supernova remnants, or other stellar corpses may indicate the previous existence of rocky planets in such former planetary systems.

Infrared signatures for the molecular building blocks of planets

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.