Fourier Transform Ion Cyclotron Resonance Spectrometry Research Articles

Aromatic substitution of halobenzenes in the gas phase: A kinetic study by FT-ICR spectrometry

Ion-molecule reactions of halobenzene radical cations with ammonia were carried out in a Fourier transform ion cyclotron resonance (FT-ICR) spectrometer. Chloro-, bromo- and iodo-benzene radical cations react with ammonia in an ipso substitution yielding anilinium ions. Fluorobenzene radical cations do not react. The reaction rates show a strong dependence on the kinetic energy of the ions. The unimolecular rate constants are (2.1±0.3) × 10 −10 cm 3 s −1 (XCl), (2.2±0.3) × 10 −10 cm 3 s −1 (XBr) and (3.8±0.5) × 10 −12 cm 3 s −1 (XI).

The kinetic energy dependence of ion/molecule collisions studied by FT-ICR spectrometry

The effect of translational excitation of reactant ions is studied in a Fourier transform ion cyclotron resonance (FT-ICR) spectrometer. It is shown that useful binding energies in ions can be deduced from the experimentally determined threshold energy values for endothermic ion/molecule reactions and for collision-induced dissociation processes.