Dissociation of Proton Bound Ketone Dimers in Asymmetric Electric Fields with Differential Mobility Spectrometry and in Uniform Electric Fields with Linear Ion Mobility Spectrometry

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• 作者：Xinxia An ; Gary A. Eiceman ; Riikka-Marjaana R盲s盲nen ; Jaime E. Rodriguez ; John A. Stone
• 刊名：The Journal of Physical Chemistry A
• 出版年：2013
• 出版时间：August 1, 2013
• 年：2013
• 卷：117
• 期：30
• 页码：6389-6401
• 全文大小：544K
• 年卷期：v.117,no.30(August 1, 2013)
• ISSN：1520-5215

文摘

The kinetics for the decomposition of the symmetrical proton-bound dimers of a series of 2-ketones (M) from acetone to 2-nonanone have been determined at ambient pressure by linear ion mobility spectrometry (IMS) and by differential mobility spectrometry (DMS). Decomposition, M₂H⁺ 鈫扢H⁺ + M, in the IMS instrument, observed under thermal conditions over the temperature range 147 to 172 掳C, yielded almost identical Arrhenius parameters E_a = 122 kJ mol^鈥? and ln A = 38.8 for the dimers of 2-pentanone, 2-heptanone, and 2-nonanone. Ion decomposition in the DMS instrument was due to a combination of thermal and electric field energies at an effective ion internal temperature whose value was estimated by reference to the IMS kinetic parameters. Decomposition was observed with radio frequency (RF) fields with maximum intensities in the range 10 kV cm^鈥? to 30 kV cm^鈥? and gas temperatures from 30 to 110 掳C, which yielded effective temperatures that were higher than the gas temperature by 260掳 at 30 掳C and 100掳 at 110 掳C. There was a mass dependence of the field for the onset of decomposition: the higher the ion mass, the higher the required field at a given gas temperature, which is ascribed to the associated increasing heat capacity with the increasing carbon number, but similar, internal vibrations and rotations.