羟基自由基双光子激发解离动力学

本文利用高里德堡态氢原子飞行时间探测技术，研究了羟基自由基的双光子激发解离动力学. H(²S)+O(¹D)和H(²S)+O(¹S)解离通道是由于羟基在经由A²Σ⁺(v''=2, J''=0.5-2.5)中间态通过双光子激发最终到排斥性的激发态势能曲线2²Ⅱ和B²Σ⁺上产生. 这两种解离通道产物都具有各向异性的角向分布，其中H(²S)+O(¹D)产物角分布异向因子β为-0.97，H(²S)+O(¹S)产物角分布异向因子β为1.97. 各向异性的角向分布与OH自由基在排斥性的激发态势能曲线上直接解离机理相吻合. 此实验观测到羟基自由基的解离能为35580±15 cm^-1.     

1-戊基的紫外光解动力学

The ultraviolet (UV) photodissociation of jet-cooled 1-pentyl radical is investigated in the wavelength region of 236-254 nm using the high-n Rydberg-atom time-of-flight (HRTOF) technique. The H-atom photofragment yield spectrum of the 1-pentyl radical shows a broad UV absorption feature peaking near 245 nm, similar to the 2p_z→3s absorption bands of ethyl and n-propyl. The center-of-mass translational energy distribution, P(E_T), of the H+C₅H₁₀ product channel is bimodal, with a slow peak at~5 kcal/mol and a fast peak at~50 kcal/mol. The fraction of the average translational energy release in the total available energy, 〈f_T〉, is 0.30, with those of the slow and fast components being 0.13 and 0.58, respectively. The slow component has an isotropic product angular distribution, while the fast component is anisotropic with an anisotropy parameter~0.4. The bimodal translational energy and angular distributions of the H+C₅H₁₀ products indicate two H-atom elimination channels in the photodissociation of 1-pentyl:(i) a direct, prompt dissociation from the electronic excited state and/or the repulsive part of the ground electronic state potential energy surface; and (ii) a unimolecular dissociation of internally hot radical in the ground electronic state after internal conversion from the electronic excited state.