Degenerate Four-Wave Mixing in Combustion Diagnostics

Since the availability of high power tunable laser sources, optical spectroscopy has gained widespread application as a diagnostic tool to detect stable and reactive species in combustion processes under a variety of environmental conditions [1]. Sensitive laser spectroscopic techniques like laser induced fluorescence (LIF) or resonance enhanced multiphoton ionization (REMPI) in the past predominantly have been applied to low pressure systems: burners that operate under several mbar of total pressure show — due to lower reaction rates — flame zones of increased spatial extent that make concentration profiling of intermediate species more accurate.