Campisi Dario, Candian Alessandra
Leiden Observatory, Leiden University, Niels Bohrweg 2, 2333 CA Leiden, The Netherlands.
Phys Chem Chem Phys. 2020 Mar 28;22(12):6738-6748. doi: 10.1039/c9cp06523g. Epub 2020 Mar 13.
Using density functional theory (DFT), we studied the formation of Stone-Wales defects in pyrene, as a prototype PAH molecule. In addition, we studied the reactivity of the defective and pristine pyrenes toward hydrogenation, a process that can occur in some regions of the interstellar medium. We found that the formation of the defect requires overcoming energies of the order of 8.4 eV, but the defective structure is stable due to the high reverse reaction barrier (approx. 6 eV). We also found that the presence of the defect decreases the sticking barrier for the first hydrogenation and promotes more stable singly and doubly hydrogenated intermediates with respect to that of the pristine pyrene. Finally, our results show that both Stone-Wales pyrene and pristine pyrenes can lead to the formation of H through an extraction mechanism involving H atoms attached on distal carbon atoms with energy barriers below 2 eV.
我们使用密度泛函理论（DFT）研究了作为多环芳烃（PAH）分子原型的芘中斯通-威尔士缺陷的形成。此外，我们还研究了有缺陷和原始芘对氢化反应的反应活性，氢化过程可能发生在星际介质的某些区域。我们发现，形成缺陷需要克服约8.4电子伏特的能量，但由于较高的逆反应势垒（约6电子伏特），有缺陷的结构是稳定的。我们还发现，缺陷的存在降低了首次氢化的吸附势垒，并促进了相对于原始芘更稳定的单氢化和双氢化中间体的形成。最后，我们的结果表明，斯通-威尔士芘和原始芘都可以通过涉及附着在远端碳原子上的氢原子的提取机制形成氢，其能垒低于2电子伏特。
