This thesis presents an experimental approach to investigate the growth of carbon particles and the mechanism of soot formation under pyrolysis conditions at atmospheric pressure by using a burner configuration of two co-annular flows called burnt-gas flow reactor (BGFR). In the present BGFR measurements, acetylene (C2H2) was used as a soot precursor. Mixtures of C2H2 diluted in nitrogen (N2) were fed through a 10 mm nozzle tube into hot post flame gases of fuel-rich ethylene (C2H4) /air flame,

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... which provides the required heat for the pyrolysis of the soot precursor. Two-color time-resolved laser-induced incandescence (TiRe-LII) was used as a non-intrusive measurement technique to monitor the formation of soot particles during the BGFR pyrolysis experiments. Using a Gülder burner, the LII setup was validated. The TiRe-LII technique was applied to investigate the increase of soot particle size (dp) and soot volume fractions (fV) quantitatively. Qualitative investigations also conducted using the LII-imaging technique on the effect of applying different inner and outer flow conditions on measured LII signal. Gas temperature was also measured using the generalized line - reverse method to characterize the pyrolysis gas flows. LII "benchmark" measurements with N2:C2H2 gas flows pave the way for testing the impacts of a fuel additive. The effect of H2 as a fuel additive was measured and the influence of CH4 as part of a binary fuel mixture on the growth of carbonaceous particles with the same burner configuration. Measured particle sizes from TiRe-LII measurements were compared with particle sizes obtained from transmission electronic microscopy (TEM) images for further validation of LII measurement findings. Soot particles were collected on TEM grids by thermophoresis. For gas-phase temperature measurements in the unburned zone of the BGFR, a nitrogen flow was seeded with toluene and the possibility of using toluene LIF for imaging thermometry was tested. The experiments showed a soot-inhibiting impact of H2 [...]