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紫外光解动力学DNCO + hv → D + NCO: 两个竞争解离通道
袁开军
作者单位E-mail
袁开军 State key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences kjyuan@dicp.ac.cn 
摘要:
我们利用D原子里德堡态时间飞行谱研究了DNCO分子在波长200-235 nm范围的光解动力学。实验测量了产物的平动能分布和空间角分布。在210-235 nm光解离下,观测到接近统计分布和各向同性的产物,该产物有可能来自于从S1势能面内转换到S0势能面,然后在S0势能面上解离。在更短的解离波长下,除了统计分布的产物,另外一种分布的产物出现在高平动能的地方,具有很高的各向异性,该产物来自于从S1势能面上的直接解离。相比较HNCO的解离结果,DNCO直接解离通道出现在更高的激发能量。通过对NCO产物内能态的归属,发现NCO产物主要是弯曲振动激发和适当的伸缩振动激发。
关键词:  光解动力学,里德堡态时间飞行谱,内转化
DOI:
分类号:
基金项目:
Ultraviolet Photodissociation Dynamics of DNCO + hv → D + NCO: Two Competitive Pathways
Yuan kai-jun
Abstract:
Photodissociation dynamics of DNCO + hv → D + NCO at photolysis wavelengths between 200 and 235 nm have been studied using the D-atom Rydberg tagging time-of-flight technique. Product translational energy distributions and angular distributions have been determined. Nearly statistical distribution of the product translational energy with nearly isotropic angular distribution was observed at 210 – 235 nm, which may come from the predissociation pathway of internal conversion from S1 to S0 state followed by decomposition on S0 surface. At shorter photolysis wavelengths, in addition to the statistical distribution, another feature with anisotropic angular distribution appears at high translational energy region, which can be attributed to direct dissociation on S1 surface. Compared with HNCO, the direct dissociation pathway for DNCO photodissociation opens at higher excitation energy. According to our assignment of the NCO internal energy distribution, dominantly bending and a little stretching excited NCO was produced via both dissociation pathways.
Key words:  Photodissociation dynamics, Rydberg tagging time-of-flight spectroscopy, Internal conversion