West Brandi, Sit Alicia, Bodi Andras, Hemberger Patrick, Mayer Paul M
Department of Chemistry, University of Ottawa , Ottawa, K1N 6N5, Canada.
J Phys Chem A. 2014 Nov 26;118(47):11226-34. doi: 10.1021/jp5085982. Epub 2014 Nov 13.
Four molecules were investigated by imaging photoelectron photoion coincidence (iPEPICO) spectroscopy: 1-propynylbenzene, indene, ethynylbenzene, and benzocyclobutene. Their threshold photoelectron spectrum was obtained and electronic transitions were assigned by OVGF (outer valence Green's function) calculations. Vibrational progressions observed in the electronic ground and excited states were simulated by calculating Franck-Condon factors based on the neutral as well as the cation ground and excited state geometries. iPEPICO was used to obtain ion dissociation data in threshold photoionization as a function of photon energy, which were modeled with RRKM theory to extract kinetic parameters for the reactions C9H8(+•) (1-propynylbezene) → C9H7(+) + H (R1); C9H8(+•) (indene) → C9H7(+) + H (R2); C8H8(+•) (benzocyclobutene) → C8H7(+) + H (R3); C8H8(+•) (benzocyclobutene) → C6H6(+) + C2H2 (R4); C8H6(+•) (1-ethynylbenzene, aka phenylacetylene) → C6H4(+) + C2H2 (R5). These results were compared to G3 level calculations. In addition, the enthalpy of formation of the indenyl radical was estimated to be ΔfH°0K = 249 ± 50 kJ mol(-1) based on a previously measured IE and a cation ΔfH°0K = 976 kJ mol(-1), determined herein.
通过成像光电子光离子符合（iPEPICO）光谱研究了四种分子：1-丙炔基苯、茚、乙炔基苯和苯并环丁烯。获得了它们的阈光电子能谱，并通过OVGF（外层价态格林函数）计算确定了电子跃迁。基于中性以及阳离子基态和激发态几何结构计算弗兰克-康登因子，对在电子基态和激发态中观察到的振动进展进行了模拟。iPEPICO用于获得阈光电离中作为光子能量函数的离子解离数据，并用RRKM理论对其进行建模，以提取反应C9H8(+•)（1-丙炔基苯）→C9H7(+) + H（R1）；C9H8(+•)（茚）→C9H7(+) + H（R2）；C8H8(+•)（苯并环丁烯）→C8H7(+) + H（R3）；C8H8(+•)（苯并环丁烯）→C6H6(+) + C2H2（R4）；C8H6(+•)（1-乙炔基苯，又名苯乙炔）→C6H4(+) + C2H2（R5）的动力学参数。将这些结果与G3水平计算进行了比较。此外，基于先前测量的电离能和本文确定的阳离子ΔfH°0K = 976 kJ mol(-1)，估计茚基自由基的生成焓为ΔfH°0K = 249 ± 50 kJ mol(-1)。
