| Microprobe laser-desorption, laser-ionization mass spectrometry (muL 2MS) is used to measure the spatial and chemical distributions of polycyclic aromatic hydrocarbons (PAHs) and related carbonaceous compounds in a variety of real and laboratory-simulated extraterrestrial samples. The combination of this sensitive microanalytical technique with this interesting group of compounds provides novel information about the chemical history of the solar system, the potential for the formation of life on other worlds, and the rich chemistry that exists in interstellar space.;This dissertation focuses first on properties of the muL 2MS technique. Factors affecting its quantitative abilities were determined. It is also shown that muL2MS samples the free organic material in meteorites, rather than the macromolecular material. Additionally, muL 2MS was modified to detect the fullerene molecule C60 in toluene solutions but proved incapable of detecting aggregated C60.;The focus of this thesis then turns to the analysis of laboratory simulations and field samples of astrochemical interest: (1) The spatial distribution and degree of alkylation of PAHs were measured in carbonaceous chondrites. The results suggest that meteoritic PAHs resulted from a common pool of compounds prior to meteoritic parent-body formation. These compounds may then have been separated chromatographically by parent-body aqueous exposure or lost by volatilization during thermal metamorphism. (2) C60 was detected in samples from three terrestrial impact craters (Sudbury, Gardnos, and Ries) using surface-enhanced laser desorption/ionization. (3) Energetic processing of interstellar ice analogs by ultraviolet radiation or high-energy proton irradiation caused the addition of a variety of side groups to the PAH coronene, as detected by muL2MS. Formation of new C-C, C-O, and C-N bonds was observed. (4) Simulations of the atmospheric chemistry of Titan showed that PAHs and nitrogen-containing aromatics may be formed in this environment. The aromatic content and extent of aromatic nitrogen incorporation detected by muL 2MS increased in tholins formed at lower pressures. (5) muL 2MS and gas chromatography-mass spectrometry (GC-MS) analysis of Siberian hydrothermal samples revealed the presence of PAHs and aliphatic hydrocarbons, with abundance and distribution varying among the sampling sites. These compounds may be of abiotic or biologic origin. |
