Guided ion beam studies of the reactions of Cr+n (n=1-18) with CO2: Chromium cluster oxide bond energies

Abstract

The kinetic energy dependence of the reactions of Cr+n (n=1-18) with CO2 are studied in a guided ion beam mass spectrometer. The primary product ions are CrnO+, which then decompose by sequential loss of chromium atoms as the kinetic energy is increased. Simple collision-induced dissociation to form the Cr+n-1, product ions is also observed. Large cluster ions, n≥9, form the CrnCO+2 adduct at low kinetic energies. For many cluster sizes, the cross section for the primary reaction, Cr+n+CO2→CrnO++CO, exhibits an interesting bimodal energy behavior that is discussed in some detail. Cr+n-O bond energies are measured and found to compare well with measurements obtained from guided ion beam studies of the Cr+n+O2 systems. The trends in this thermochemistry are discussed and compared to bulk phase oxidation values. © 1998 American Institute of Physics.