Bouallagui A, Zanchet A, Bañares L, García-Vela A
Laboratoire de Spectroscopie Atomique, Moléculaire et Applications-LSAMA LR01ES09, Faculté des Sciences de Tunis, Université de Tunis El Manar, 2092, Tunis, Tunisia.
Instituto de Física Fundamental, Consejo Superior de Investigaciones Científicas, Serrano 123, 28006 Madrid, Spain.
Phys Chem Chem Phys. 2022 Mar 23;24(12):7387-7395. doi: 10.1039/d2cp00180b.
Photodissociation of the vinyl radical through pathways CHCH → CHC + H, CHCH → CHCH + H, and CHCH → CH + CH is investigated by means of high-level calculations. Potential-energy curves (PECs) along the corresponding dissociating bond distance associated with the ground and several excited electronic states involved in the above fragmentation pathways, as well as the nonadiabatic couplings connecting the different states, are obtained. The findings of several experiments on vinyl photodissociation performed at different excitation wavelengths are analyzed and explained qualitatively in the light of the present PECs. A two-dimensional representation (consisting of radial and angular coordinates to represent one of the H atoms of the CH group) is also used to calculate the electronic states. The surfaces obtained reflect a rich variety of conical intersections, exit barriers, and nonadiabatic couplings leading to predissociation in different regions of energy and of the two coordinates, suggesting a complex photodissociation dynamics of the CHCH → CHCH + H pathway, with rather different fragmentation mechanisms involved. The two-dimensional results also provide interesting information on the mechanism of in-plane hydrogen migration from the CH group to the CH one through a high-lying transition state.
通过高水平计算研究了乙烯基自由基通过CHCH → CHC + H、CHCH → CHCH + H和CHCH → CH + CH途径的光解离。获得了与上述碎片化途径中涉及的基态和几个激发电子态相关的沿相应解离键距离的势能曲线（PEC），以及连接不同态的非绝热耦合。根据目前的PEC，对在不同激发波长下进行的几个乙烯基光解离实验的结果进行了定性分析和解释。还使用了二维表示法（由径向和角坐标组成，用于表示CH基团中的一个H原子）来计算电子态。得到的表面反映了丰富多样的锥形交叉点、出射势垒和非绝热耦合，导致在能量和两个坐标的不同区域发生预解离，这表明CHCH → CHCH + H途径的光解离动力学很复杂，涉及相当不同的碎片化机制。二维结果还提供了关于通过高能过渡态使CH基团中的氢向CH基团进行面内氢迁移机制的有趣信息。
