Low-energy reactions of dications with atoms and molecules

State-selective, energy- and angle-resolved collisional interactions of CF 2 2 + dications with atomic and molecular gases are studied at low collision energies. Single-electron transfer measurements help resolve the prevailing ambiguity vis-a-vis the lowest ionization energy of CF 2 + , yielding a value of 20.55 ± 0.5 eV. Ground state ( 1 Σ g + ) CF 2 2 + captures an electron from Ar, D2, N2 and CF4 predominantly into the ground 6a1 orbital of CF2+ but in CF 2 2 + – O 2 and H2O collisions, the dominant capture channel is the excited (4b2) orbital of CF 2 + . Data are qualitatively interpreted using ‘reaction windows’ calculated using the Landau–Zener and extended over-the-barrier models.