Jaddi A, Marakchi K, Zanchet A, García-Vela A
Laboratory of Spectroscopy, Molecular Modeling, Materials, Nanomaterials, Water and Environment, LS3MN2E/CERNE2D, Faculty of Sciences, Mohammed V University in Rabat, Rabat, Morocco.
Instituto de Física Fundamental, Consejo Superior de Investigaciones Científicas, Serrano 123, 28006 Madrid, Spain.
J Chem Phys. 2024 Jun 14;160(22). doi: 10.1063/5.0207362.
Acetaldehyde is a very relevant atmospheric species whose photodissociation has been extensively studied in the first absorption band both experimentally and theoretically. Very few works have been reported on acetaldehyde photodissociation at higher excitation energies. In this work, the photodissociation dynamics of acetaldehyde is investigated by means of high-level multireference configuration interaction ab initio calculations. Five different fragmentation pathways of acetaldehyde are explored by calculating the potential-energy curves of the ground and several excited electronic states along the corresponding dissociating bond distances. The excitation energy range covered in the study is up to 10 eV, nearly the ionization energy of acetaldehyde. We intend to rationalize the available experimental results and, in particular, to elucidate why some of the studied fragmentation pathways are experimentally observed in the different excitation energy regions and some others are not. Based on the shape of the calculated potential curves, we are able to explain the main findings of the available experiments, also suggesting possible dynamical dissociation mechanisms in the different energy regions. Thus, the reported potential curves are envisioned as a useful tool to interpret the currently available experiments as well as future ones on acetaldehyde photodissociation at excitation wavelengths in the range studied here.
乙醛是一种非常重要的大气物种，其光解离在首个吸收带已通过实验和理论进行了广泛研究。关于乙醛在更高激发能下的光解离报道极少。在这项工作中，通过高水平多参考组态相互作用从头算计算研究了乙醛的光解离动力学。通过计算基态和几个激发电子态沿相应解离键距离的势能曲线，探索了乙醛的五种不同裂解途径。研究涵盖的激发能范围高达10电子伏特，接近乙醛的电离能。我们旨在使现有的实验结果合理化，特别是阐明为什么在不同激发能区域中一些研究的裂解途径在实验中被观察到，而其他一些则未被观察到。基于计算得到的势能曲线形状，我们能够解释现有实验的主要发现，还能提出不同能量区域中可能的动态解离机制。因此，所报道的势能曲线被视为一种有用的工具，可用于解释目前关于在此研究范围内激发波长下乙醛光解离的现有实验以及未来的实验。
