Reactions of atomic and molecular ions with acetone, 1,1,1-trifluoroacetone, and hexafluoroacetone: An investigation of the effects of molecular structure on the dynamics and kinetics of ion–molecule reactions

• Ion reactions with acetone, 1,1,1-trifluoroacetone, and hexafluoroacetone.
• Effects of molecular structure on the dynamics of ion–molecule reactions.
• New reaction rate coefficients and product ion branching ratios.

A selected ion flow tube study of the reactions of a series of gas-phase atomic cations (S+, Xe+, O+, Kr+, N+, Ar+ and Ne+) and molecular ions (SFn+ (n = 1–5), CFn+ (n = 1–3), CF2Cl+, H3O+, NO+, N2O+, CO2+, CO+, and N2+) spanning a large range of recombination energies (6.3–21.6 eV), with acetone, 1,1,1-trifluoroacetone, and hexafluoroacetone has been undertaken with the objective of exploring the nature of the reaction ion chemistry as the methyl groups in acetone are substituted for CF3. The reaction rate coefficients and product ion branching ratios for all 66 reactions, measured at 298 K, are reported. The experimental reaction rate coefficients are compared to theoretically calculated collisional values. Several distinct reaction processes were observed among the large number of reactions studied, including charge transfer (non-dissociative and dissociative), abstraction, ion–molecule associations and, in the case of the reactions involving the reagent ion H3O+, proton transfer.

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