Final-state-resolved mutual neutralization in I+ - I− collisions
Résumé
We have studied the mutual neutralization reaction of atomic iodine ions (i.e., I++I−→I+I) in a cryogenic double electrostatic ion-beam storage-ring apparatus. Our results show that the reaction forms iodine atoms either in the ground-state configuration (I(5p5 2P0), ∼40%) or with one atom in an electronically excited state (I(6s2 [2]), ∼60%), with no significant variation over the branching ratios in the studied collision-energy range (0.1–0.8 eV). We estimate the total charge-transfer cross section to be of the order of 10-13cm2 at 0.1 eV collision energy. Ab initio relativistic electronic structure calculations of the potential-energy curves of I2 suggest that the reaction takes place at short internuclear distances. The results are discussed in view of their importance for applications in electric thrusters.