A shock tube, laser-schlieren study of the pyrolysis of isobutene: Relaxation, incubation, and dissociation rates

摘要: Dissociation, vibrational relaxation, and unimolecular incubation have all been observed in shock waves isobutene with the laser-schlieren technique. Experiments covered a wide range of high-temperature conditions: 900–2300 K, post-incident pressures from 7 to 400 torr 2, 5, 10% mixtures krypton. The surprising observation is that well resolved over full temperature range. process completely exponential, relaxation times 20–120 ns atm. Relaxation dissociation are clearly separated for T > 1850 estimated near 200 Incubation essential modeling very low-pressure decomposition. Modeling gradients chain mechanism initiated by CH fission produces an excellent fit accurate rates show severe falloff. A restricted-rotor, Gorin-model RRKM analysis fits these quite known bond-energy as barrier 〈ΔE〉down = 680 cm−1. extrapolated k∞ log k∞(s−1) 19.187–0.865 −87.337 (kcal/mol)/RT, good agreement previous work. © 2003 Wiley Periodicals, Inc. Int J Chem Kinet 35: 381–390,