Dissociative Recombination of CH4+

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• 作者：Richard D. Thomas ; Iryna Kashperka ; E. Vigren ; Wolf D. Geppert ; Mathias Hamberg ; Mats Larsson ; Magnus af Ugglas ; Vitali Zhaunerchyk
• 刊名：Journal of Physical Chemistry A
• 出版年：2013
• 出版时间：October 3, 2013
• 年：2013
• 卷：117
• 期：39
• 页码：9999-10005
• 全文大小：314K
• 年卷期：v.117,no.39(October 3, 2013)
• ISSN：1520-5215

文摘

CH₄⁺ is an important molecular ion in the astrochemistry of diffuse clouds, dense clouds, cometary comae, and planetary ionospheres. However, the rate of one of the common destruction mechanisms for molecular ions in these regions, dissociative recombination (DR), is somewhat uncertain. Here, we present absolute measurements for the DR of CH₄⁺ made using the heavy ion storage ring CRYRING in Stockholm, Sweden. From our collision-energy dependent cross-sections, we infer a thermal rate constant of k(T_e) = 1.71(卤0.02) 脳 10^鈥?(T_e/300)^{鈭?.66(卤0.02)} cm^3聽s^鈥?聽over the region of electron temperatures 10 鈮?T_e 鈮?1000 K. At low collision energies, we have measured the branching fractions of the DR products to be CH₄ (0.00 卤 0.00); CH₃ + H (0.18 卤 0.03); CH₂ + 2H (0.51 卤 0.03); CH₂ + H₂ (0.06 卤 0.01); CH + H₂ + H (0.23 卤 0.01); and CH + 2H₂ (0.02 卤 0.01), indicating that two or more C鈥揌 bonds are broken in 80% of all collisions.