Investigations of particle loaded flames are of considerable interest in combustion diagnostics for understanding the basic processes and models for numerical simulations. In addition, particle loaded flames are important for technical applications, e.g. for the synthesis of ultra pure fused silica using flame deposition or the generation of nanoparticles for sensors and catalytic converters.
Laser Induced Fluorescence (LIF) allows a very sensitive and selective determination of concentration fields by excitation of molecules and radicals in the flames such as OH, O2 and NO. It is difficult to apply this measurement technique to flames loaded with particles. Typical substances for flame pyrolysis (HMDSO, SiCl4, GeCl4, SnCl4, TiCl4) show broadband absorption and an increase of scattering at the excitation laser wavelength. Using special filtering as well as modified excitation wavelengths (e.g. pulse-to-pulse wavelength switching) we are able to measure two-dimensional OH and temperature distributions, e.g., in SiCl4 loaded H2/O2-flames (figure on the left).