Geminate Charge Recombination in Liquid Alkane with Concentrated CCl4: Effects of CCl4 Radical Anion and Narrowing of Initial Distribution of Cl鈥?/sup>

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• 作者：Akinori Saeki ; Naoto Yamamoto ; Yoichi Yoshida ; Takahiro Kozawa
• 刊名：Journal of Physical Chemistry A
• 出版年：2011
• 出版时间：September 15, 2011
• 年：2011
• 卷：115
• 期：36
• 页码：10166-10173
• 全文大小：983K
• 年卷期：v.115,no.36(September 15, 2011)
• ISSN：1520-5215

文摘

Dynamics of radical cations and electrons in an admixture of a linear saturated hydrocarbon (n-dodecane) and halocarbon (carbon tetrachloride, CCl₄) were investigated by picosecond electron beam pulse radiolysis. The decay of thermalized electrons (e_th^{鈥?/sup>) observed in infrared transient photoabsorption were simply accelerated by the addition of CCl₄, giving a high rate constant of 2.3 脳 1011 mol鈥? dm3 s鈥?. The decrease of the initial yield of e_th鈥?/sup> was quantified by C₃₇ (50 mmol), which is linked to the reaction of epithermal electrons (e鈥?/sup>) with CCl₄. In contrast, the n-dodecane radical cation (RH₂鈥?) monitored in the near-infrared indicated a convex-type dependence of the decay rate on CCl₄ concentration, although the initial yield of RH₂鈥? remained almost constant up to a much higher CCl₄ concentration. The decay of RH₂鈥? was analyzed by Monte Carlo simulations of geminate ion recombination with e_th鈥?/sup>, chlorine anion (Cl鈥?/sup>) formed via dissociative electron attachment, and CCl₄ radical anion. The results showed a good agreement with the experiments by considering two assumptions: (1) CCl₄ radical anion formed via e_th鈥?/sup> attachment and (2) narrowing of the initial distribution of Cl鈥?/sup>. The decrease in the initial yield of RH₂鈥? at high CCl₄ concentration was well explained by immediate decomposition of CCl₄鈥? to CCl₃+ and hole transfer from CCl₄鈥? to adjacent RH₂ without diffusive motion of the reactants. Time-dependent density functional theory supported the spectroscopic assignment of intermediate species in the n-dodecane/CCl₄ system. The present results would be of help in understanding the electron capture reaction in multicomponent systems such as a chemically amplified resist in lithography.}