A STUDY OF SOME GAS-PHASE LANTHANIDE PLUS OXIDANT CHEMIIONIZATION REACTIONS WITH CHEMIELECTRON SPECTROSCOPY

An investigation has been made of some gas-phase lanthanide plus oxidant chemiionization reactions with electron spectroscopy. The oxidants used were O2 (X3 SIGMA(g)-), O2 (a1 DELTA(g)) and O (3P) and the lanthanide metals (Ln) studied were Pr, Nd, Sm, Eu and Gd. In the case of europium, no ions or electrons were observed for the Eu + O2 (X3 SIGMA(g)-), Eu + O2 (a1 DELTA(g)) and Eu + O (3P) reactions. For the other four lanthanides, studies of the equivalent metal oxidation reactions showed that when each metal is reacted with discharged oxygen, the dominant chemiionization channel is the associative ionization reaction Ln + O (3P) --> LnO+ + e-. In each case, this conclusion was supported by comparison of available standard enthalpies for possible chemiionization reactions with the observed high kinetic energy offset of the observed chemielectron band, as well as by mass analysis of the ions produced. Results of earlier studies made by electron spectroscopy of the reactions of Ce and La with O2 (X3 SIGMA(g)-), O2 (a1 DELTA(g)) and O (3P) are discussed in the light of results obtained in this work.