Approach for a quantitative on-the-fly fluorescence diagnostic in combustion systems.

The combination of a megahertz repetition rate, picosecond dye laser and gated photon counting detection is used to obtain sodium atom fluorescence lifetimes in seeded atmospheric pressure CH(4)/O(2)/diluent flames. Data acquisition times as short as 1 ms (on-the-fly) are demonstrated with a 3.8-MHz laser rep rate. The area under the fluorescence temporal profiles following laser excitation divided by the fluorescence lifetime is shown to provide a measure of sodium concentration independent of quenching environment.