High-resolution photoemission mapping of the three-dimensional band structure of Bi(111)

Abstract

Angle-resolved photoemission spectra of Bi(111) excited with synchrotron radiation at photon energies from 9 to 100 eV have been used to determine the initial- and final-state band structures along $\mathrm{\ensuremath{\Gamma}}T$. Deviations from the free-electron dispersion for energies below about 60 eV can be accounted for by an energy-dependent extension function to the final-state bands. The experimentally determined dispersion of the top three bulk valence bands is compared with literature data and various band-structure calculations, none of which satisfactorily describes the observed band width, the critical-point energies, or their specific dispersion relations ${E}_{i}(k)$. At a photon energy of 29 eV, direct transitions lead to a pronounced final-state gap. In this region, the experimental band-structure map consists of features resembling the one-dimensional density-of-states projection of the Bi bulk band structure onto the (111) surface.