The first ionization potentials of the transition metals

The appearance potentials of the transition metals yttrium through molybdenum, ruthenium through palladium, and lanthanum through platinum have been determined by electron impact. A method of simultaneous and intercomparative measurements with known standards was used. Corrections to the appearance potentials for thermally excited levels in the atoms and for possible ionization paths to other than the ground states of the ions are discussed and used to deduce the ionization potentials.