Particle Inception in a Laminar Premixed Benzene Flame

Spectral optical techniques, including light extinction and laser induce fluorescence and incandescence measurements, are combined to characterize large-molecule soot precursors and soot in a slightly sooting flame of benzene at atmospheric pressure. Light absorption coupled to in-situ light scattering measurements and ex-situ Atomic Force Microscopy also allowed the evaluation of particle sizes. In the benzene flame high molecular mass structures with typical sizes of 3–4nm are formed in the main oxidation region of the flame. The radical-rich flame environment in which these compounds are formed promotes their dehydrogenation increasing the level of their aromaticity. As a result, nanoparticles with typical sizes of about 5 nm, absorbing and fluorescing in the visible are formed. These compounds reach a maximum concentration just before the appearance of incandescent soot particles.