Institute of Physical and Theoretical Chemistry , University of Wuerzburg , Am Hubland Süd, 97074 Würzburg , Germany.
Radboud University , Institute for Molecules and Materials, FELIX Laboratory , Toernooiveld 7-c , 6525 Nijmegen , the Netherlands.
J Phys Chem A. 2019 Nov 7;123(44):9573-9578. doi: 10.1021/acs.jpca.9b09153. Epub 2019 Oct 23.
The three isomers of the xylyl radical, CH, are possible intermediates in the formation of soot and polycyclic aromatic hydrocarbons (PAH). Their infrared spectra have been recorded by IR/UV ion dip spectroscopy using free electron laser radiation. The radicals were generated by flash pyrolysis from the corresponding nitrites and resonantly ionized via the D ← D transition around 310 nm. Mid-infrared spectra of the three xylyl isomers were recorded between 550 and 1700 cm and are in excellent agreement with computations, provided that overtones and combination bands are included in the simulation. The results show that the three xylyl isomers can be distinguished by their infrared spectra and that no isomerization occurs in the pyrolysis reactor. The IR spectra obtained at / = 208 indicate that dimerization of xylyl radicals leads to substituted stilbenes, which has not been observed for benzyl.
三种二甲苯自由基异构体，CH，可能是烟尘和多环芳烃（PAH）形成的中间产物。它们的红外光谱通过使用自由电子激光辐射的 IR/UV 离子陷光谱法记录下来。自由基通过相应的亚硝酸盐的闪光热解产生，并通过 310nm 左右的 D ← D 跃迁共振离子化。三种二甲苯异构体的中红外光谱在 550 至 1700cm 之间记录，并与计算结果非常吻合，前提是包括了泛频和组合带。结果表明，三种二甲苯异构体可以通过它们的红外光谱来区分，并且在热解反应器中没有发生异构化。在 /= 208 处获得的 IR 光谱表明，二甲苯自由基的二聚化导致取代的二苯乙烯，而这在苄基中没有观察到。
