GAS-PHASE METAL OXIDATION REACTIONS STUDIED BY CHEMIELECTRON SPECTROSCOPY AND CHEMIION MASS-SPECTROMETRY - REACTIONS OF CERIUM AND LANTHANUM WITH O2(X3-SIGMA-G), O2(A1-DELTA) AND O(3P)

The gas-phase reactions M + O2(X 3-SIGMA-g-), M + O2(a 1-delta-g)an and M + O(3P) have been studied with chemielectron spectroscopy, where M represents one of the lanthanide metals, cerium or lanthanum. Assignment of the observed bands has been assisted by mass analysis of the ions produced and by approximate kinetic modelling calculations. For the M + O2(X 3-SIGMA-g-) and M + O2(a 1-detla-g) associative ionization reactions, most of the excess energy appears as electron kinetic energy, whereas for the M + O(3P) reactions a larger fraction of the reaction energy is retained in the positive ion.