Experimental Study of Diamond Formation in Astrophysical Environments

• Applicant: Dr. Cornelia Jäger
• Subject Area: Astrophysics and Astronomy
• Term: from 2015 to 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 281937660

Diamond represents a major part of the carbonaceous cosmic dust. However the formation route of cosmic diamond is not well understood. The present project is devoted to the study of diamond formation at conditions which are similar to those found in the interstellar medium and stellar envelops including evolved stars, protoplanetary, and planetary environments. The project consists of two strongly related tranches. In the first part, we will study the erosion of carbon material in hydrogen-rich, cosmic environments. We will study the etching of graphite, amorphous carbon, and diamond material by atomic and molecular hydrogen at temperatures ranging from 10 K to 1400 K. These temperatures represent the formation conditions in various astrophysical environments. In low-temperature conditions, UV irradiation will be used to facilitate the erosion. These data will provide important information on the chemical stability of carbonaceous and diamond grains in the different astrophysical regions. In the second part of the project, the obtained erosion data will be applied for the finding of appropriate astrophysical condensation conditions of diamond. Atomic hydrogen and carbon, which belong to the most abundant species in our Universe, will be used for the study of the chemical vapor deposition process of diamond. The deposition conditions of diamond will mimic astrophysical conditions. The atomic carbon and hydrogen flows will be simultaneously directed and deposited onto an appropriate substrate such as silicon wafer or diamond seeded crystals. We will use a newly developed atomic carbon source, which provides an intense and pure flux of low-energy atomic carbon. The diamond growth will be monitored in situ by Raman spectroscopy. Further characterization of the deposit will be performed using infrared, ultraviolet, and visible absorption spectroscopy, and high-resolution transmission electron microscopy. The evaluation of the experimental results with regard to astrophysical formation conditions enables us to predict the astrophysically relevant sites of efficient diamond formation and the formation pathways.

• DFG Programme: Research Grants
• International Connection: France
• Co-Investigators: Dr. Roland Gredel; Professor Dr. Thomas Henning; Dr. Harald Mutschke; Professor Marc Georg Willinger, Ph.D.; Dr. Svitlana Zhukovska
• Cooperation Partner: Privatdozent Dr. Johannes Berndt