From PAHs to Solid Carbon

Carbonaceous grains represent a major component of cosmic dust. The review will summarize new results in laboratory investiga- tions of carbonaceous dust components. The nanometer-sized carbon particles are supposed to represent a blend of differently structured carbon including graphitic, diamond-like, fullerene-like and chain-like components on a subnanometer or nanometer scale. Recent models used to explain the structure of gas-phase condensed carbon nano- particles are discussed. Possible formation pathways of carbonaceous grains from molecular components and clusters and the role of poly- cyclic aromatic hydrocarbons (PAHs) and fullerenes are disclosed.