Ammonia measurements with femtosecond laser-induced plasma spectroscopy

Femtosecond laser-induced plasma spectroscopy for in situ ammonia (NH₃) measurements was demonstrated in NH₃/N₂ mixtures. When a femtosecond laser at 800 nm was focused at the flow field, the parent NH₃ molecules would be photolyzed to generate electronics excited NH fragments, and then indirect measurements of NH₃ could be realized by detecting the NH fluorescence (A³Π-X³Σ^-) at 336 nm. A detection limit of 205 ppm was achieved. This work is the first attempt, to the best of our knowledge, for ammonia measurements with a femtosecond laser, and the results are useful for the development of ammonia diagnostics.