title: Hybrid femtosecond/picosecond coherent anti-Stokes Raman scattering for high-speed gas-phase thermometry.
abstract: We demonstrate hybrid femtosecond/picosecond (fs/ps) coherent anti-Stokes Raman scattering for high-speed thermometry in unsteady high-temperature flames, including successful comparisons with a time- and frequency-resolved theoretical model. After excitation of the N(2) vibrational manifold with 100 fs broadband pump and Stokes beams, the Raman coherence is probed using a frequency-narrowed 2.5 ps probe beam that is time delayed to suppress the nonresonant background by 2 orders of magnitude. Experimental spectra were obtained at 500 Hz in steady and pulsed H(2)-air flames and exhibit a temperature precision of 2.2% and an accuracy of 3.3% up to 2400 K. Strategies for real-time gas-phase thermometry in high-temperature flames are also discussed, along with implications for kilohertz-rate measurements in practical combustion systems.
authors.affiliation: Department of Mechanical Engineering, Iowa State University, Ames, Iowa 50011, USA.
authors.forename: Joseph D
authors.initials: JD
authors.lastname: Miller
authors.forename: Mikhail N
authors.initials: MN
authors.lastname: Slipchenko
authors.forename: Terrence R
authors.initials: TR
authors.lastname: Meyer
authors.forename: Hans U
authors.initials: HU
authors.lastname: Stauffer
authors.forename: James R
authors.initials: JR
authors.lastname: Gord
mesh_terms: D005740:Gases; D008962:Models, Theoretical; D055585:Physical Phenomena; D013059:Spectrum Analysis, Raman / Q000379:methods*; D013696:Temperature; D014732:Vibration
chemical_list: D005740:Gases