Collision-induced dissociation of Fen+ (n=2-10) with Xe: Ionic and neutral iron binding energies
Abstract
Cross sections for collision-induced dissociation (CID) of Fe n+ with Xe, 2≤n≤10, are presented. Experiments were performed on a newly constructed guided ion beam mass spectrometer, the design and capabilities of which are described in detail. The single mechanism for dissociation of iron cluster ions is sequential loss of iron atoms with increasing collision energies. There is no evidence for fission to molecular neutral products. The cross section threshold energy dependences are analyzed to give the bond dissociation energies (BDEs), D0(Fen-1+-Fe). Data analysis employs an empirical model that incorporates RRKM theory to account for inefficient dissociation on the time scale of the experiment. Results show that Fe6+ has the strongest BDE, D0(Fe5+-Fe) = 3.44 ± 0.18 eV, while Fe3+ is the most weakly bound, D0(Fe 2+-Fe) = 1.64 ± 0.15 eV. Neutral cluster BDEs are derived from ionic binding energies and known ionization potentials. Branching ratios and other cross section features are also discussed with respect to cluster size. © 1989 American Institute of Physics.