Electronic excitations in the transition metals V, Zr, Nb, Mo, and Ta

The np core-loss spectra and the associated deexcitation processes for the transition metals V (<i>n=3</i>), Zr, Nb, Mo (<i>n=4</i>), and Ta (<i>n=5</i>) have been studied in low-energy electron scattering experiments in order to investigate the dependence of their nature on the principle quantum number <i>n</i>. For the metals with <i>n=3</i> and <i>n=4</i>, the measurements are accounted for in terms of atomic transitions involving the excitation and the decay of localized <i>d</i> electrons. The observations on V can qualitatively be compared with published computations for isolated atoms. While the <i>5p</i> core excitations for Ta resemble the gross features of the unoccupied d-band density of states, the decay processes involve, besides the conventional O₂VV and O₃VV Auger transitions, autoionization emission related to 5<i>p⁶</i>5<i>d^N</i>-5<i>p⁵</i>5<i>d^N+1</i>-5<i>p⁶</i>5<i>d^N-1</i>+ε<i>f</i> transitions.