Rate constants for D + C 2H 4 → C 2H 3D + H at high temperature: implications to the high pressure rate constant for H + C 2H 4 → C 2H 5

Abstract

The shock tube technique with H- and D-atom atomic resonance absorption spectrometry detection has been used to study the reaction, D + C 2 H 4 → C 2 H 3 D + H over the temperature range, 1153–1616 K. The rate constants for this reaction were found to be temperature dependent with k = (2.56 ± 0.46) × 10 −10 exp (−2797 ± 239K/ T) cm 3 molecule −1 s −1 with the errors being at the one standard deviation level. The present data have been combined with earlier lower temperature determinations, and the joint database has been examined with theory that includes both an ab initio determination of the potential energy surface and an evaluation of the rate constants using the RRKM theory. Similar calculations have been made for the analogous all-H reaction. For both isotopic combinations, the agreement between theory and experiment is good, allowing a new estimate from theory for the high-pressure limit for H + C 2H 4 → C 2H 5 of 0.420 × 10 −15 T 1.75 exp (−604.9 K/ T) cm 3 molecule −1 s −1 for 200–2000 K. Since the D + C 2H 4 measurements reported here are the only high temperature measurements for either isotopic combination, the new high-pressure limiting estimate should be the best available at high temperatures.