title: Interference-free gas-phase thermometry at elevated pressure using hybrid femtosecond/picosecond rotational coherent anti-Stokes Raman scattering.
abstract: Rotational-level-dependent dephasing rates and nonresonant background can lead to significant uncertainties in coherent anti-Stokes Raman scattering (CARS) thermometry under high-pressure, low-temperature conditions if the gas composition is unknown. Hybrid femtosecond/picosecond rotational CARS is employed to minimize or eliminate the influence of collisions and nonresonant background for accurate, frequency-domain thermometry at elevated pressure. The ability to ignore these interferences and achieve thermometric errors of <5% is demonstrated for N2 and O2 at pressures up to 15 atm. Beyond 15 atm, the effects of collisions cannot be ignored but can be minimized using a short probe delay (~6.5 ps) after Raman excitation, thereby improving thermometric accuracy with a time- and frequency-resolved theoretical model.
authors.affiliation: Department of Mechanical Engineering, Iowa State University, Ames, IA 50011, USA.
authors.forename: Joseph D
authors.initials: JD
authors.lastname: Miller
authors.forename: Chloe E
authors.initials: CE
authors.lastname: Dedic
authors.forename: Sukesh
authors.initials: S
authors.lastname: Roy
authors.forename: James R
authors.initials: JR
authors.lastname: Gord
authors.forename: Terrence R
authors.initials: TR
authors.lastname: Meyer
mesh_terms: D017076:Computer-Aided Design; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005740:Gases / Q000737:chemistry*; D008027:Light; D044367:Phase Transition; D011312:Pressure; D012542:Scattering, Radiation; D013059:Spectrum Analysis, Raman / Q000295:instrumentation*; D018511:Systems Integration; D013817:Thermography / Q000295:instrumentation* / Q000379:methods*; D013821:Thermometers
chemical_list: D005740:Gases