Spectroscopic characterisation of carbonaceous nanoparticles in premixed flames

This work deals with the characterisation of the carbonaceous aerosols prod uced in a combustion source. These particles can be connected to the black and primary organic carbon aerosols found in the atmosphere. Premixed fuel rich laminar flames in sooting and non-sooting regimes of combustion are ex amined UV-visible light absorption laser-excited fluorescence, laser-induce d incandescence and light scattering. The analysis of the spectroscopic mea surements leads to the formulation of a model for the aerosol formed in fla me consisting of a background matrix, with mono-ring sub-units connected by aliphalic bonds, that contains inclusions made of two aromatic rings and, in some cases, soot-like black carbon. With this model, the use of the scat tering/absorption technique allows us to estimate the mean dimension and co ncentration of such particles. The most important finding of this paper is that carbon containing aerosol with typical size around 2 nm are formed als o in non-luminous flames where elemental black carbon is absent and that si milar particles are precursors for soot particles which are produced by the ir coagulation. (C) 1999 Elsevier Science Ltd. All rights reserved.