Diamond, aromatic, aliphatic components of interstellar dust grains: Random covalent networks in carbonaceous grains

Abstract

view Abstract Citations (15) References (30) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Diamond, Aromatic, and Aliphatic Components of Interstellar Dust Grains: Random Covalent Networks in Carbonaceous Grains Duley, W. W. Abstract A formalism based on the theory of random covalent networks (RCNs) in amorphous solids is developed for carbonaceous dust grains. RCN solutions provide optimized structures and relative compositions for amorphous materials. By inclusion of aliphatic, aromatic, and diamond clusters, solutions specific to interstellar materials can be obtained and compared with infrared spectral data. It is found that distinct RCN solutions corresponding to diffuse cloud and molecular cloud materials are possible. Specific solutions are derived for three representative objects: VI Cyg No. 12, NGC 7538 (IRS 9), and GC IRS 7. While diffuse cloud conditions with a preponderance of sp2 and sp3 bonded aliphatic CH species can be reproduced under a variety of RCN conditions, the presence of an abundant tertiary CH or diamond component is highly constrained. These solutions are related quantitatively to carbon depletions and can be used to provide a quantitative estimate of carbon in these various dust components. Despite the abundance of C6 aromatic rings in many RCN solutions, the infrared absorption due to the aromatic stretch at approximately 3.3 micrometers is weak under all conditions. The RCN formalism is shown to provide a useful method for tracing the evolutionary properties of interstellar carbonaceous grains. Publication: The Astrophysical Journal Pub Date: May 1995 DOI: 10.1086/175691 Bibcode: 1995ApJ...445..240D Keywords: Aliphatic Hydrocarbons; Carbonaceous Materials; Cosmic Dust; Covalence; Diamonds; Infrared Absorption; Interstellar Matter; Absorptivity; Chemical Analysis; Covalent Bonds; Hydrogen Bonds; Astrophysics; ISM: DUST; EXTINCTION; INFRARED: ISM: LINES AND BANDS; ISM: CLOUDS full text sources ADS | data products SIMBAD (5)