Lee Kyoung-Seok, Lee Keon Woo, Kim Tae Kyu, Ryoo Ryong, Jung Kyung-Hoon
Department of Chemistry and School of Molecular Science (BK21), Korea Advanced Institute of Science and Technology, Daeduck Science Town, Daejeon 305-701, Korea.
J Chem Phys. 2005 Jan 15;122(3):34308. doi: 10.1063/1.1825994.
The photodissociation dynamics of vinyl bromide and perfluorovinyl bromide have been investigated at 234 nm using a photofragment ion imaging technique coupled with a state-selective [2+1] resonance-enhanced multiphoton ionization scheme. The nascent Br atoms stem from the primary C-Br bond dissociation leading to the formation of C2H3(X) and Br(2Pj;j=1/2,3/2). The obtained translational energy distributions have been well fitted by a single Boltzmann and three Gaussian functions. Boltzmann component has not been observed in the perfluorovinyl bromide. The repulsive 3A'(n,sigma ) state has been considered as the origin of the highest Gaussian components. Middle translational energy components with Gaussian shapes are produced from the 1A"(pi,sigma) and/or 3A"(pi,sigma*) which are very close in energy. Low-energy Gaussian components are produced via predissociation from the 3A'(pi,pi*) state. The assignments have also been supported by the recoil anisotropy corresponding to the individual components. It is suggested that intersystem crossing from the triplet states to the ground state has been attributed to the Boltzmann component and the fluorination reduces the probability of this electronic relaxation process.
利用光碎片离子成像技术结合态选择[2+1]共振增强多光子电离方案，在234nm波长下研究了溴乙烯和全氟溴乙烯的光解离动力学。新生的Br原子源于初级C-Br键的解离，导致形成C2H3(X)和Br(2Pj;j=1/2,3/2)。所获得的平动能分布已用单个玻尔兹曼函数和三个高斯函数进行了很好的拟合。在全氟溴乙烯中未观察到玻尔兹曼分量。排斥性的3A'(n,σ*)态被认为是最高高斯分量的起源。具有高斯形状的中等平动能分量由能量非常接近的1A"(π,σ*)和/或3A"(π,σ*)产生。低能高斯分量是通过从3A'(π,π*)态预解离产生的。这些归属也得到了与各个分量相对应的反冲各向异性的支持。有人提出，从三重态到基态的系间窜越归因于玻尔兹曼分量，而氟化作用降低了这种电子弛豫过程的概率。
