Laboratory analogs of carbonaceous matter: Soot and its precursors and by-products

Abstract

Carbonaceous materials have been prepared in the laboratory by laser-induced pyrolysis of a mixture of hydrocarbons under different conditions and laser ablation of graphite in reactive gas atmospheres. We have investigated the soluble and insoluble parts of the condensed carbon powders with several spectroscopic and chromatographic methods in order to obtain information on the composition of the condensate. The results of these experiments have demonstrated that, at temperatures lower than 1700 K, the pyrolysis by-products are mainly PAHs, whereas at higher temperatures fullerenes and polyyne-based compounds are formed. The experimental findings point to different soot formation mechanisms with variable intermediates and end products. It has been found that soot extracts can contain more than 65 different polycyclic aromatic hydrocarbons (PAHs). Eventually, the study of the condensation pathways of soot particles and their precursors and by-products will permit the prediction of the spectral properties of carbonaceous matter in space. © 2008 International Astronomical Union.