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.