Collisional broadening and shifting parameters of the Raman Q branch of H₂ perturbed by N₂ determined from speed-dependent line profiles at high temperatures

The broadening and shifting of the Q branch of H₂ diluted in N₂ are studied at temperatures between 300 and 1200 K. (i) In order to account for the observed anomalies (asymmetric profiles and nonlinearity of the linewidth versus perturber concentration), the results are interpreted using a speed-dependent model in its general form. This model introduces the speed dependence of the shift and the broadening. In contrast with the previous H₂–rare-gas studies, the high-temperature measurements prove the necessity to include speed-dependent broadening that was ignored in the previous studies. (ii) Concomitantly, we report as well pure H₂ results including Raman frequencies for the Q(7–9) lines and broadening and shifting results at 800 and 1200 K. A consistent set of data is deduced for H₂-N₂ up to 1200 K and the proposed model would be pertinent at higher temperatures for combustion applications. © 1996 The American Physical Society.