Dynamics of the reaction of C-3(a(3) Pi(u)) radicals with C2H2: A new source for the formation of C5H

作者：Huang Wen Jian; Sun Yi Lun; Chin Chih Hao; Lee Shih Huang^*

来源：Journal of Chemical Physics, 2014, 141(12): 124314.

DOI：10.1063/1.4896618

The reaction C-3(a(3) Pi(u)) + C2H2. C5H + H was investigated at collision energy 10.9 kcal mol- 1 that is less than the enthalpy of ground- state reaction C3( X1 +/- g+) + C2H2. C5H + H. C-3(a(3) Pi(u)) radicals were synthesized from 1% C4F6/ He by pulsed high- voltage discharge. The title reaction was conducted in a crossed molecular- beam apparatus equipped with a quadrupole- mass filter. Product C5H was interrogated with time- of- flight spectroscopy and synchrotron vacuum- ultraviolet ionization. Reactant C-3(a(3) Pi(u)) and product C5H were identified using photoionization spectroscopy. The ionization thresholds of C3( X1 +/- g+) and C-3(a(3) Pi(u)) are determined as 11.6 +/- 0.2 eV and 10.0 +/- 0.2 eV, respectively. The C5H product is identified as linear pentynylidyne that has an ionization energy 8.4 +/- 0.2 eV. The title reaction releases translational energy 10.6 kcal mol- 1 in average and has an isotropic product angular distribution. The quantum- chemical calculation indicates that the C-3(a(3) Pi(u)) radical attacks one of the carbon atoms of C(2)H(2)and subsequently a hydrogen atom is ejected to form C5H + H, in good agreement with the experimental observation. As far as we are aware, theC(3)(a(3) Pi(u)) + C2H2 reaction is investigated for the first time. This work gives an implication for the formation of C5H from the C-3(a(3) Pi(u)) + C2H2 reaction occurring in a combustion or discharge process of C2H2.

• 出版日期2014-9-28