CO2 chirped-probe-pulse femtosecond CARS thermometry

The application of CO2 chirped-probe-pulse (CPP) fs coherent anti-Stokes Raman scattering (CARS) for flame thermometry is discussed. A phenomenological model for CO2/O2 CPP fs CARS was developed, and the simulations showed the potential for CO2 temperature measurements free of interferences from O2 and with no contribution from the nonresonant background by using a long-time delay for the chirped probe pulse. The accuracy and precision for CO2 CPP fs CARS thermometry is compared with N2 CPP fs CARS thermometry for temperatures between 295 K and 1420 K. The measurement accuracy for the CO2 measurements is comparable with that for the N2 measurements, while the precision for the CO2 temperature measurements is significantly better at lower temperatures. In conclusion, we also demonstrate that accurate flame thermometry using a single set of laser parameters can be achieved using the delayed CPP approach.