The reactions of H₃O⁺, NO⁺ and O₂⁺ ions with a homologous series of six aliphatic ketones, viz. acetone through 2-octanone, have been investigated in a helium-buffered selected ion flow-drift tube, SIFDT, in order to reveal their dependencies on ion–molecule interaction energies, E_r, and to gain insight into their mechanisms. The ultimate motivation is to allow analysis and absolute quantification of trace amounts of ketones and other volatile organic compounds in air using selected ion flow-drift tube mass spectrometry, SIFDT-MS. The reactions of H₃O⁺ with the ketone molecules, M, proceed via exothermic proton transfer producing MH⁺ ions, the collisional rate coefficients, k_c, for which can be calculated as a function of E_r and are seen to reduce by about one third over the E_r range from 0.05 eV up to 0.5 eV. The rate coefficients, k, and product ion distributions for the NO⁺ and O₂⁺ reactions with M had to be obtained experimentally relative to the calculated k_c for the H₃O⁺ reactions. The product ions of the NO⁺/ketones reactions initially proceed via the formation of excited (NO⁺M)* adduct ions that partially fragment, and the k reduces with E_r as much as four times for the acetone reactions but remains close to their respective k_c for the higher-order ketones indicating long lifetimes of the (NO⁺M)* ions with respect to the stabilising collision times with He atoms. The k for the O₂⁺/ketones dissociative charge transfer reactions are observed to be greater than their calculated k_c implying that long distance electron transfer occurs.

中文翻译：

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选定离子流漂移管中离子-分子相互作用能提高时的离子化学：H ₃ O ⁺，NO ⁺和O ₂ ⁺与饱和脂肪族酮的反应

H ₃ O ⁺，NO ⁺和O ₂ ⁺离子与六个脂族酮的同源系列的反应，即。为了揭示它们对离子-分子相互作用能E _r的依赖性，并深入了解了它们的机理，已经在氦缓冲的选定离子流漂移管SIFDT中研究了通过2-辛酮的丙酮。最终的动机是允许使用选定的离子流漂移管质谱仪SIFDT-MS对空气中的痕量酮和其他挥发性有机化合物进行分析和绝对定量。H ₃ O ⁺与酮分子M的反应通过产生MH ⁺离子的放热质子转移，其碰撞速率系数k _c可以作为E _r的函数来计算，并且在从0.05 eV至0.5 eV的E _r范围内，大约减少了三分之一。与M的NO ⁺和O ₂ ⁺反应的速率系数k和产物离子分布必须相对于H ₃ O ⁺反应的计算k _c通过实验获得。NO ⁺ /酮反应的产物离子最初通过形成的激发（NO ⁺ M）*加合物离子会部分碎裂，对于丙酮反应，k随E _r降低多达四倍，但对于较高级的酮，其k k仍接近各自的k _c，表明该化合物的使用寿命长。 （NO ⁺ M）*离子与He原子稳定碰撞时间的关系。该ķ用于将O ₂ ⁺ /酮解离的电荷转移反应被观察为比其更大的计算ķ _Ç暗示长距离电子转移发生。