Third-order ion-molecule clustering reactions

Reactions of metal cluster anions with inorganic and organic molecules in the gas phase

Progress on the activation and transformation of important inorganic and organic molecules by negatively charged bare metal clusters as well as ligated systems with oxygen, carbon, and nitrogen, among others.

Electron Transfer and Ligand Addition to Atomic Mercury Cations in the Gas Phase: Kinetic and Equilibrium Studies at 295 K

Results are reported for experimental measurements of the room-temperature chemical reactions between ground-state Hg*+ ions and 16 important environmental and biological gases: SF6, CO, CO2, N2O, D2O, CH4, CH3F, O2, CH3Cl, OCS, CS2, NH3, C6F6, NO2, NO*, and C6H6. The inductively coupled plasma/selected-ion flow tube tandem mass spectrometer used for these measurements has provided both rate and equilibrium constants. Efficient electron transfer (>19%) is observed with CS2, NH3, C6F6, NO2, NO*, and C6H6, molecular addition occurs with D2O, CH4, CH3F, CH3Cl, and OCS, and SF6, CO, CO2, N2O, and O2 showed no measurable reactivity with Hg*+. Theory is used to explore the stabilities and structures of both the observed and unobserved molecular adducts of Hg*+, and reasonable agreement is obtained with experimental observations, given the uncertainties of the theory and experiments. A correlation is reported between the Hg*+ and proton affinities of the ligands investigated. Solvation of Hg*+ with formic acid was observed to increase the rate of electron transfer from NO* by more than 20%.

Alkali-metal ion/molecule association reactions and their applications to mass spectrometry

This review will be concerned primarily with thermal alkali-metal ion association reactions of the general type: A+ + M + N reversible (A + M)+ + N. Where A denotes a positively charged alkali metal ion, M is neutral species and N works as a third body. As indicated, most association reactions are reversible, and the A-M bond derives primarily from electrostatic forces whose energy (affinity) is typically 50 kcal/mol or less, often much less. The review includes reaction mechanism, instrumentation, and application to mass spectrometry, together with reaction rates and alkali ion affinities of the classified compounds.

Resonant laser ablation as a selective metal ion source for gas-phase ion molecule reactions

Resonant laser ablation (RLA) is used as a source to selectively generate multiple metal ion species from the same sample. The capability of rapidly changing metal ions for gas-phase ion chemistry studies is a significant advantage in ion-molecule chemistry. The simple experimental arrangement uses relatively modest laser pulse energies (≤ 25 µJ/pulse) from a tunable dye laser to desorb and selectively ionize different metal atoms from a multicomponent sample. In turn, this allows the chemistry of several components to be investigated without breaking vacuum or altering the experimental geometry. This work demonstrates the use of RLA as a selective source of several reagent metal ions for gas-phase ion chemistry investigations. In particular, the reactivity of acetone with Cr(+), Fe(+), Ni(+), and Cu(+) was examined for metal ions selectively created by RLA from a standard steel sample.