Direct measurement of S-branch N₂-H₂ Raman linewidths using time-resolved pure rotational coherent anti-Stokes Raman spectroscopy

S-branch N₂-H₂ Raman linewidths have been measured in the temperature region 294–1466 K using time-resolved dual-broadband picosecond pure rotational coherent anti-Stokes Raman spectroscopy (RCARS). Data are extracted by mapping the dephasing rates of the CARS signal temporal decay. The J-dependent coherence decays are detected in the time domain by following the individual spectral lines as a function of probe delay. The linewidth data set was employed in spectral fits of N₂ RCARS spectra recorded in binary mixtures of N₂ and H₂ at calibrated temperature conditions up to 661 K using a standard nanosecond RCARS setup. In this region, the set shows a deviation of less than 2% in comparison with thermocouples. The results provide useful knowledge for the applicability of N₂ CARS thermometry on the fuel-side of H₂ diffusion flames.