First ionization potentials of some refractory oxide vapors

Abstract

The ionization potentials of the gaseous atoms, monoxides, and dioxides over the refractory oxides of Ti, Zr, Hf, Th, U, Y, and La have been obtained from ionization efficiency curves and appearance potentials by electron impact. A method of simultaneous and intercomparative measurements with known standards was used. The measured values for the gaseous metal atoms are in agreement with the spectroscopic values except for Zr and Hf which are about 0.4 eV lower. These results and some of previous studies show that the values for the monoxides are somewhat less than those for the metals, and the dioxides of those metals in their highest oxidation state are generally larger by 3–4 eV.