Bremsstrahlung isochromat spectra and density-of-states calculations for the3dand4dtransition metals

Abstract

We present the results of a systematic investigation of the empty electronic states up to 10 eV above $E_F$ in the $3d$ and $4d$ transition metals with the use of bremsstrahlung isochromat spectroscopy (BIS). We compare these data to calculations of the unoccupied densities of states. The agreement between theoretical and experimental $d$-band widths and peak positions is quite good, although small discrepancies (≲0.5 eV) are found for the early transition metals. The unoccupied bandwidths are usually larger for the $4d$ than for the $3d$ metals and decrease from left to right across the Periodic Table, except where magnetic ordering of the $3d$ elements is important. A prominent steplike spectral feature observed at 7-10 eV above $E_F$ in all spectra is attributed to a critical point in the band structure. The BIS spectra in the region up to 10 eV above $E_F$ are not strongly affected by electron-energy-loss effects. Discrepancies between one-particle densities of states and the spectral response are smaller for BIS than for photoemission in these elements.