A new flowing afterglow-guided ion beam tandem mass spectrometer. Applications to the thermochemistry of polyiodide ions

A new flowing afterglow-guided ion beam tandem mass spectrometer has been constructed. The tandem mass spectrometer has a linear quadrupole-octopole-quadrupole geometry. The apparatus has been successfully tested for the measurement of reaction rates and endothermic reaction thresholds. The new instrument has been used to determine 0 K bond strengths in two polyiodide ions: D(I 2 −I − ) = 126 ± 6 kJ/mol and D(I 2 −I 3 − ) = 49 ± 6 kJ/mol. These values compare well to recent computational results. Electron affinity (EA)(I 3 ) = 4.15 ± 0.12 eV can be derived from this work and values in the literature.