Temperature measurement in gas mixtures by femtosecond Raman-induced polarization spectroscopy

The potential of femtosecond Raman-induced polarization spectroscopy (RIPS) for the simultaneous determination of temperature and concentrations was investigated. These measurements were related to the rotational time response of the molecular gas mixture, which was measured as a function of the pump-probe time delay. The change of the polarizability anisotropy with respect to the vibrational levels was taken into account. The results of temperature measurements in pure CO₂ showed good agreement with the values obtained by a thermocouple. The RIPS technique was also applied to a CO ₂-N₂ gas mixture to determine simultaneously temperatures and concentrations at temperatures up to 600 K. The accuracy and the feasibility of the method applied to highest temperatures are discussed.