Description
Amorphous carbon-based networks naturally occur in interstellar dust and are largely responsible for enriching the Earth with the elements of life in the form of carbonaceous chondrite meteorites. Complex organic molecules containing oxygen and nitrogen have also been detected in extraterrestrial carbon networks including in carbon-rich asteroids, Bennu and Ryugu. Carbon networks are heavily utilised as electrodes, solid state sensors, and protective coatings for manufacturing and aerospace. In recent years, amorphous carbon networks doped with oxygen and nitrogen have gained popularity, offering enhanced surface reactivity, electrical conductivity, and chemical stability. This presentation covers our fundamental research into amorphous organic systems with the inclusion of oxygen and nitrogen. We have synthesised the amorphous organic networks by plasma enhanced chemical vapour deposition in a dielectric barrier discharge. In particular, we are interested in how modification by ion impacts and annealing affect the composition of the amorphous product. We have found the initial conditions that capture the most oxygen and nitrogen in the amorphous carbon, by selecting the best input gas mixing ratios, pressure and voltage of deposition through the use of vibrational spectroscopies. We found the pathway by which aliphatic structures transform to aromatic structures through graphitization enabled by vacuum annealing. We characterise this process as an ordering of carbon atoms, from a 3-dimensionally amorphous to a 2-dimensionally crystalline structure, complemented by ab-intio molecular dynamics models. We determine that the deposition process involves fractal aggregation revealed as a “cauliflower-like” surface morphology reminiscent of interstellar dust particles. Finally, we discuss how an interdisciplinary approach that includes laboratory synthesis, vibrational spectroscopy and microscopy and ab-initio molecular dynamics can provide an in-depth understanding of how amorphous organic materials are formed and modified.
| I am the presenting author | Yes |
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