Aromatic And Aliphatic Organic Materials In Solar System Objects

The “Unidentified Infrared Emission(UIE) Bands” are a distinctive set of emission features at 3.3, 6.2, 7.7, 8.6 and 11.3 micron. They are ubiquitously seen in a wide variety of astrophysical environments. In addition, 3.4, 6.85, 12.7, 16.4, 17.4micron features also detected weak emission lines. The “Unidentified Infrared Emission(UIE) Bands” at 3.3, 6.2, 7.7, 8.6 and 11.3 micron usually attributed to polycyclic aromatic hydrocarbons(PAH) molecules. Carrier models of the“Unidentified Infrared Emission(UIE) Bands” considered 3.3 micron radiation from the aromatic C–H stretching vibration. If we could assume that all 3.4 micron radiation from the aliphatic C–H stretching vibration, we could use the observed intensities of the 3.3 and 3.4 micron emission features in astrophysical environments to estimate the aliphatic fraction of the UIE carriers composition(i.e., the fraction of carbon atoms in aliphatic form).Scientists observed 3.3 micron and 3.4 micron spectral features in many astrophysical environments. In this thesis we select spectra of Comet, Titan, Hyperion and Iapetus to analyze and estimate the aliphatic and the aromatic organic materials of those bodies. Because of the lack of 3.4 micron spectral features, Titan is not considered in the final calculation results. In addition, two spectra were also selected to represent the situation of galaxy interstellar space.In this thesis we obtained here an average value of A3.3 / A3.4≈0.94 by analyzing a number of related organic molecules(A3.4 and A3.3 are, respectively, the band strengths of the 3.4 μm aliphatic and 3.3 μm aromatic C–H bonds) based on attributing 3.4 μm and 3.3 μm to characteristic wavelength of aliphatic and aromatic structure C–H stretching modes, respectively. We also analyzed those astrophysical environments exhibiting both the 3.3 μm and 3.4 μm C–H features and determine I3.4 /I3.3, the ratio of the radiation flow from the 3.4 μm feature to that from the 3.3 μm feature. Finally, we obtained their aliphatic fraction by applying the value of A3.3 / A3.4and I3.4 / I3.3.