Exploring the dynamics of reaction N(2D)+C2H4 with crossed molecular-beam experiments and quantum-chemical calculations

Abstract

We conducted the title reaction using a crossed molecular-beam apparatus, quantum-chemical calculations, and RRKM calculations. Synchrotron radiation from an undulator served to ionize selectively reaction products by advantage of negligibly small dissociative ionization. We observed two products with gross formula C₂H₃N and C₂H₂N associated with loss of one and two hydrogen atoms, respectively. Measurements of kinetic-energy distributions, angular distributions, low-resolution photoionization spectra, and branching ratios of the two products were carried out. Furthermore, we evaluated total branching ratios of various exit channels using RRKM calculations based on the potential-energy surface of reaction N(²D)+C₂H₄ established with the method CCSD(T)/6-311+G(3df,2p)//B3LYP/6-311G(d,p)+ZPE[B3LYP/6-311G(d,p)]. The combination of experimental and computational results allows us to reveal the reaction dynamics. The N(²D) atom adds to the CC π-bond of ethene (C₂H₄) to form a cyclic complex c-CH₂(N)CH₂ that directly ejects a hydrogen atom or rearranges to other intermediates followed by elimination of a hydrogen atom to produce C₂H₃N; c-CH₂(N)CH+H is the dominant product channel. Subsequently, most C₂H₃N radicals, notably c-CH₂(N)CH, further decompose to CH₂CN+H. This work provides results and explanations different from the previous work of Balucani et al. [J. Phys. Chem. A, 2000, 104, 5655], indicating that selective photoionization with synchrotron radiation as an ionization source is a good choice in chemical dynamics research.