Photodissociation Dynamics of 2-Bromopropane Using Velocity Map Imaging Technique

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• 作者：Rongshu Zhu ; Bifeng Tang ; Xiu Zhang ; Bing Zhang
• 刊名：Journal of Physical Chemistry A
• 出版年：2010
• 出版时间：June 3, 2010
• 年：2010
• 卷：114
• 期：21
• 页码：6188-6193
• 全文大小：183K
• 年卷期：v.114,no.21(June 3, 2010)
• ISSN：1520-5215

文摘

Photodissociation dynamics of 2-bromopropane in the A band was investigated at several wavelengths between 232 and 267 nm using resonance-enhanced multiphoton ionization technique combined with velocity map ion-imaging detection. The ion images of Br (²P_3/2) and Br* (²P_1/2) were analyzed to yield corresponding total translational energy and angular distributions. The total translational energy distributions showed that the channel leading to Br carried more internal energy in the 2-C₃H₇ moiety than the channel leading to Br*. The anisotropy parameters of β (Br) were obtained to be between 0.68 and 1.49, and β (Br*) between 0.73 and 1.96, indicating that the Br* product originates from direct excitation of the ³Q₀ state and the ¹Q₁ → ³Q₀ nonadiabatic transition, and the Br product from direct excitation of the ¹Q₁ or ³Q₁ state and the ³Q₀ → ¹Q₁ nonadiabatic transition. The curve crossing probabilities were determined to be increase with the wavelength. As compared with the case of CH₃Br, the two heavier branched CH₃ groups significantly enhance the Br (²P_3/2) production from nonadiabatic contribution. The curve crossing from the ³Q₀ to the ¹Q₁ surface is much higher than that of the reverse from the ¹Q₁ to the ³Q₀ surface, which may have resulted from the difference in shape between the potential energy surfaces of the ³Q₀ and ¹Q₁ states. Finally, based on the experimental data, the partial absorption cross sections of the A band for the ³Q₀, ³Q₁, and ¹Q₁ states were extracted.