The X-Ray Spectra Arising from the Valence Band—LTransitions of Tungsten, Tungsten Oxide (WO3) and Platinum

Abstract

X-ray emission lines and absorption edges arising from transitions between the $L$ levels and the valence bands of tungsten, tungsten oxide (W${\mathrm{O}}_3$) and platinum were studied with a double crystal spectrometer. Manning and Chodorow's calculation of the density of states in the $5d$ and $6s$ bands of tungsten is found to be in good agreement with the observed shapes of the tungsten absorption edges. The tungsten emission lines, on the other hand, do not have the structure expected from their calculation and are 4.5 ev narrower than the region of occupied states calculated for these bands. A comparison of the spectra of tungsten metal with those of its oxide shows: (1) the initial absorption maximum of the $L_{\mathrm{II}}$ and $L_{\mathrm{III}}$ edges is both broader and higher in the oxide, (2) the $L$ edges of the oxide are shifted 2.5 ev to higher frequencies, (3) the emission lines of the oxide are about 3 ev wider than those of the metal. These differences between the spectra of the oxide and the metal are explained qualitatively in terms of the high electronegativity of oxygen. The platinum absorption edge structures observed are in agreement with what is qualitatively expected from the other properties of this metal. A marked difference in the relative intensity of corresponding structure features of the $L_{\mathrm{II}}$ and $L_{\mathrm{III}}$ edges is ascribed to a spin-orbit coupling of the valence electrons.