PLASMA PROCESSING OF INTERSTELLAR PAHS INTO SOLAR-SYSTEM KEROGEN

Processes resulting in the formation of hydrocarbons of carbonaceous c hondrites and the identity of the interstellar molecular precursors in volved are an objective of investigations into the origin of the solar system and perhaps even life on earth. We have combined the resources and experience of an astronomer and physicists doing laboratory simul ations with those of a chemical expert in the analysis of meteoritic h ydrocarbons, in a project that investigated the conversion of polycycl ic aromatic hydrocarbons (PAHs) formed in stellar atmospheres into alk anes found in meteorites. Plasma hydrogenation has been found in the U niversity of Alabama at Birmingham Astrophysics Laboratory to produce from the precursor PAH naphthalene, a new material having an IR absorp tion spectrum (Lee, W. and Wdowiak, T.J., Astrophys. J. 417, L49-L51, 1993) remarkably similar to the obtained at Arizona State University o f the benzene-methanol extract of the Murchison meteorite (Cronin, J.R . and Pizzarello, S., Geochim. Cosmochim. Acta 54, 2859-2868, 1990). T here are astrophysical and meteoritic arguments for PAH species from e xtra-solar sources being incorporated into the solar nebula, where pla sma hydrogenation is highly plausible. Conversion of PAHs into alkanes could also have occurred in the interstellar medium. The synthesis of laboratory analogs of meteoritic hydrocarbons through plasma hydrogen ation of PAH species is underway, as is chemical analysis of those ana logs. The objective is to clarify this heretofore uninvestigated proce ss and to understand its role during the origin of the solar system as a mechanism of production of hydrocarbon species now found in meteori tes. Results have been obtained in the form of time-of-flight spectros copy and chemical analysis of the lab analog prepared from naphthalene .