Parsons Bradley F, Jayson Cameron J, Szpunar David E, Cook Mark M
Department of Chemistry, Creighton University, 2500 California Plaza, Omaha, Nebraska 68178, United States.
Department of Chemistry, University of Wisconsin-Stevens Point, 2101 Fourth Avenue, Stevens Point, Wisconsin 54481, United States.
J Phys Chem A. 2021 Apr 29;125(16):3406-3414. doi: 10.1021/acs.jpca.1c01920. Epub 2021 Apr 14.
Our primary goal was to measure the NO (A) photoproduct appearance energy and ground-state dissociation energy of the N-NO complex. We recorded velocity map ion images of NO photofragments resulting from the dissociation of the N-NO complex excited between ∼225.8 and 224.0 nm, which ranged from the photodissociation threshold to about 342 cm above the threshold. In the experiment, one photon dissociated the complex through the N (X Σ)-NO (A Σ) ← N (X Σ)-NO (X Π) transition, and a second photon nonresonantly ionized the NO (A) photoproduct. The lowest-energy photons near 225.8 nm did not have sufficient energy to photodissociate the lowest excited state of the complex; however, dissociation was observed with increasing photon energy. On the basis of the experiments, we determined the appearance energy for the NO (A) photoproduct to be 44 284.7 ± 2.8 cm. From the appearance energy and the NO A ← X origin band transition, we determined a ground-state dissociation energy of 85.8 ± 2.8 cm. As we increased the photon energy, the excess energy was partitioned into rotational modes of the diatomic products as well as product translational energy. We found good agreement between the average fraction of rotational energy and the predictions of a simple pseudo three atom impulsive model. Finally, at all photon energies, we observed some contribution from internally excited complexes in the resulting (E). The maximum internal energy of these complexes was consistent with the ground-state dissociation energy.
我们的主要目标是测量N-NO络合物的NO (A) 光产物出现能和基态离解能。我们记录了在约225.8至224.0 nm之间激发的N-NO络合物解离产生的NO光碎片的速度映射离子图像，该波长范围从光解离阈值到高于阈值约342 cm。在实验中，一个光子通过N (X Σ)-NO (A Σ) ← N (X Σ)-NO (X Π) 跃迁使络合物解离，第二个光子非共振电离NO (A) 光产物。225.8 nm附近能量最低的光子没有足够的能量使络合物的最低激发态光解离；然而，随着光子能量的增加，观察到了解离现象。基于这些实验，我们确定NO (A) 光产物的出现能为44 284.7 ± 2.8 cm。根据出现能和NO A ← X起源带跃迁，我们确定基态离解能为85.8 ± 2.8 cm。随着我们增加光子能量，多余的能量被分配到双原子产物的转动模式以及产物平动能量中。我们发现转动能量的平均分数与简单的伪三原子脉冲模型的预测之间有很好的一致性。最后，在所有光子能量下，我们在所得产物中观察到来自内部激发络合物的一些贡献。这些络合物 的最大内能与基态离解能一致。
