Abstract
The x-ray absorption spectrum at the edges of tantalum has been measured on two spectrometers that are equipped with: (i) a conventional bremsstrahlung source and a LiF(200) crystal, and (ii) a synchrotron source and a channel-cut Si(220) crystal. Our results are similar to those reported by earlier workers except that the apparatus (ii) yields a Ta spectrum of the highest resolution reported thus far. Of particular interest is the sharp spike (white line) occurring at the and but not at the edge. We associated the white line with an atomiclike allowed transition from the or state to the vacant states of a high density. However, a quantitative comparison with the calculated band structure can not be made because none of the existing calculations has included the effect of a core hole. In an attempt to understand the white lines, we present two least-squares analyses of the Ta edge in terms of (a) a Lorentzian profile and (b) a Breit-Wigner-Fano-type formula. The latter, which was first suggested by Cauchois and Mott, appeared to provide a better fit to the asymmetric line shape.
- Received 3 August 1978
DOI:https://doi.org/10.1103/PhysRevB.19.679
©1979 American Physical Society