Zhang Zhiguo, Xin Min, Xin Yu, Zhao Shutao, Jin Yanling, Wu Guorong, Dai Dongxu, Chen Zhichao, Sakkoula Evangelia, Parker David H, Yuan Kaijun, Yang Xueming
Key Laboratory of Functional Materials and Devices for Informatics of Anhui Higher Education Institutions and School of Physics and Electronic Engineering, Fuyang Normal University, Fuyang, Anhui, 236037, China.
State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, Liaoning, 116023, China.
Phys Chem Chem Phys. 2022 Oct 19;24(40):25018-25024. doi: 10.1039/d2cp04020d.
State-to-state photodissociation of CO( = 0 and 1) at 157 nm the O(D) + CO(Σ) channel was studied by using the sliced velocity map imaging technique. Both the O(D) and CO(Σ) products were detected by (2 + 1) resonance enhanced multiphoton ionization (REMPI). Detection of CO the Σ ←← Σ transition allowed ro-vibrational state-selective detection, and combined with imaging, the fragment energy and angular distributions have been derived. For CO( = 0 and 1|) products from the CO( = 0) molecule, the angular distributions of low- CO display positive anisotropic parameters (about 0.8); with increasing, the product anisotropic parameters gradually reduce to zero. While for CO( = 0 and 1|) products from the vibrational excited CO( = 1) molecule, the angular distributions of low- CO also display positive anisotropic parameters; with increasing, the product anisotropic parameters first decrease to zero and then become negative (about -0.5). Experimental results show that the observed variation of the product angular distribution with the rotational quantum number of CO is consistent with trends predicted by a classical model for non-axial fragment recoil. The results support advanced theoretical predictions of a predominantly parallel transition to the bent 2A' excited state of CO, where bending introduces torque during the direct dissociation process.
利用切片速度映射成像技术研究了在157nm波长下CO（ν = 0和1）的态间光解离至O（D）+ CO（Σ）通道。通过（2 + 1）共振增强多光子电离（REMPI）检测O（D）和CO（Σ）产物。对CO的Σ←←Σ跃迁的检测实现了振转态选择性检测，结合成像，得到了碎片能量和角分布。对于来自CO（ν = 0）分子的CO（ν' = 0和1|）产物，低转动量子数CO的角分布显示出正的各向异性参数（约为0.8）；随着转动量子数增加，产物各向异性参数逐渐减小至零。而对于来自振动激发的CO（ν = 1）分子的CO（ν' = 0和1|）产物，低转动量子数CO的角分布也显示出正的各向异性参数；随着转动量子数增加，产物各向异性参数先减小至零，然后变为负（约为-0.5）。实验结果表明，观察到的产物角分布随CO转动量子数的变化与非轴向碎片反冲经典模型预测的趋势一致。这些结果支持了先进的理论预测，即主要平行跃迁到CO的弯曲2A'激发态，其中弯曲在直接解离过程中引入了扭矩。
