Femtosecond time resolved coherent anti-Stokes Raman spectroscopy: Experiment and modelization of speed memory effects on H-2-N-2 mixtures in the collision regime

Ha Tran (1) , Pierre Joubert (1) , L. Bonamy (1) , Bruno Lavorel (2) , Vincent Renard (2) , Frédéric Chaussard (2) , Olivier Faucher (2) , B. Sinardet (2)

1 LPM - Laboratoire de Physique Moléculaire (UMR 6624)
2 LPUB - Laboratoire de Physique de l'Université de Bourgogne

With the aim of temperature diagnostic, femtosecond time-resolved CARS (coherent anti-Stokes Raman spectroscopy) is applied to probe H-2 in H-2-N-2 mixtures. In a first part, a Lorentzian profile is used to model the femtosecond CARS response. A difference between the experimental broadening and the expected one is observed in the collision regime. The observed broadening increases strongly in an inhomogeneous way with respect to the perturber concentration. This is of considerable importance for temperature measurements. In a second part, we show that in the collision regime, this inhomogeneous broadening is due to the speed dependence of the collisional parameters and the memory effects of the radiator speed. A new modelization of the time-resolved CARS response taking into account the speed memory effects is presented and applied to the temperature diagnostic in H-2-N-2 mixtures. The numerical results are in good agreement with experiments.

Mots clés: INDUCED POLARIZATION SPECTROSCOPY; CHANGING COLLISIONS; DOPPLER; H-2; CONSEQUENCES; TEMPERATURE; SHIFT; CARS; VIBRATIONAL LINE-PROFILES; GAS-MIXTURES

Domaines: Optique [physics.optics]

Ha Tran, Pierre Joubert, L. Bonamy, Bruno Lavorel, Vincent Renard, et al.. Femtosecond time resolved coherent anti-Stokes Raman spectroscopy: Experiment and modelization of speed memory effects on H-2-N-2 mixtures in the collision regime. Journal of Chemical Physics, 2005, 122, pp.194317. ⟨10.1063/1.1894020⟩. ⟨hal-00400398⟩