Sun Z F, Farooq Z, Parker D H, Martin P J J, Western C M
Institute for Molecules and Materials , Radboud University Nijmegen , Heyendaalseweg 135 , 6525 AJ Nijmegen , The Netherlands.
School of Chemistry , University of Bristol , Cantock's Close , BS8 1TS Bristol , U.K.
J Phys Chem A. 2019 Aug 15;123(32):6886-6896. doi: 10.1021/acs.jpca.9b05350. Epub 2019 Aug 2.
Photodissociation of vibrationally and electronically excited sulfur dimer molecules (S) has been studied in a combined experimental and computational quantum chemistry study in order to characterize bound-continuum transitions. Ab initio quantum chemistry calculations are carried out to predict the potential energy curves, spin-orbit coupling, transition moments, and bound-continuum spectra of S for comparison with the experimental data. The experiment uses velocity map imaging to measure S-atom production following S photoexcitation in the ultraviolet region (320-205 nm). A pulsed electric discharge in HS produces ground-state S XΣ( = 0-15) as well as electronically excited singlet sulfur and bΣ( = 0, 1), and evidence is presented for the production and photodissociation of S aΔ. In a previous paper, we reported threshold photodissociation of SXΣ( = 0) in the 282-266 nm region. In the present study, S(P) fine structure branching and angular distributions for photodissociation of S (XΣ( = 0), aΔ and bΣ) via the B″Π, BΣ and 1Π excited states are reported. In addition, photodissociation of the XΣ( = 0) state of S to the second dissociation limit producing S(P) + S(D) is characterized. The present results on S photodynamics are compared to those of the well-studied electronically isovalent O molecule.
为了表征束缚态-连续态跃迁，在一项结合实验和计算量子化学的研究中，对振动和电子激发的硫二聚体分子（S₂）的光解离进行了研究。开展了从头算量子化学计算，以预测S₂的势能曲线、自旋轨道耦合、跃迁矩和束缚态-连续态光谱，以便与实验数据进行比较。该实验使用速度成像技术来测量在紫外区域（320 - 205 nm）S₂光激发后产生的S原子。在HS中进行脉冲放电会产生基态S₂ X³Σ₉⁺（v = 0 - 15）以及电子激发的单重态硫和b³Σ₉⁺（v = 0, 1），并且给出了S₂ a¹Δ的产生和光解离的证据。在之前的一篇论文中，我们报道了在282 - 266 nm区域内S₂ X³Σ₉⁺（v = 0）的阈值光解离。在本研究中，报道了通过B″¹Π、B³Σ⁻和¹Π激发态对S₂（X³Σ₉⁺、a¹Δ和b³Σ⁻）进行光解离时的S(P)精细结构分支和角分布。此外，还对S₂ X³Σ₉⁺（v = 0）态光解离至产生S(P) + S(D)的第二个解离极限进行了表征。将目前关于S₂光动力学的结果与研究充分的电子等价位氧分子的结果进行了比较。
