Shapero Mark, Ramphal Isaac A, Neumark Daniel M
Chemical Sciences Division , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States.
Department of Chemistry , University of California, Berkeley , Berkeley , California 94720 , United States.
J Phys Chem A. 2018 May 3;122(17):4265-4272. doi: 10.1021/acs.jpca.7b11837. Epub 2018 Apr 23.
The photodissociation of jet-cooled cyclopentadienyl radicals, c-CH, at 248 nm was studied using photofragment translational spectroscopy. Two dissociation channels were observed: H + CH and CH + CH. The CH fragment was identified as ethynylallene by its ionization energy. The translational energy distribution determined for each channel suggests that both dissociation mechanisms occur via internal conversion to the ground electronic state followed by intramolecular vibrational redistribution and dissociation. The experimental branching ratio and RRKM (Rice-Ramsperger-Kassel-Marcus) calculations favor the formation of CH + CH over the H-atom loss channel. The RRKM calculations also support the observation of ethynylallene as the dominant CH product isomer.
利用光碎片平动光谱研究了在248 nm波长下喷射冷却的环戊二烯基自由基（c-CH）的光解离。观察到两个解离通道：H + CH和CH + CH。通过其电离能将CH碎片鉴定为乙炔基丙二烯。为每个通道确定的平动能分布表明，两种解离机制都是通过内转换到基态电子态，随后进行分子内振动再分配和解离而发生的。实验分支比和RRKM（赖斯-拉姆齐格-卡塞尔-马库斯）计算结果表明，相比于氢原子损失通道，CH + CH的形成更占优势。RRKM计算结果也支持将乙炔基丙二烯作为主要的CH产物异构体这一观察结果。
