Flame characterization by femtosecond CARS
Fs-CARS transients from nitrogen molecules in a flame (e.g. methane/air) are used for temperature analysis [1]. The expanded section of the transient shown at the bottom demonstrates excellent the agreement between fit and experiment.
[1] P. Beaud, H.-M. Frey, T. Lang, and M. Motzkus, Chem. Phys. Lett. 344 (2001) 405 - 412.
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The derived temperature values depend on the collision model used in the fit. Fs-CARS enables measurements in pressurized environments and experimentally provides an access to the appropriate model [2].
[2] G. Knopp, P. Beaud, P.P. Radi,M. Tulej, B. Bougie, D. Cannavo, and T. Gerber, Journal of Raman Spectrosc.,33 (2002) 861.
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Figure: Fitted temperature and pressure values from fs CARS signals at 295 K. Two different models for energy transfer (ECS-E and ECS-P) are compared.
