Bromine metallization studied by X-ray absorption spectroscopy

Abstract:

Bromine has been studied up to a pressure of 110 GPa by X-ray absorption spectroscopy (XAS) at the bromine K-edge, that allows to measure the pressure evolution of the width of the unoccupied conduction band. At GPa we observe a slope change in the evolution of this width. Comparison with published calculations of the electronic density of states indicates that the physical origin of the slope change is compatible with the metallisation process. This is also confirmed by a simple tight binding calculation. In addition, the metallisation pressure value is in agreement with calculated ones. At GPa a discontinuity in the evolution of the width of the sigma antibonding band points out the onset of a phase transformation. This result is compatible with the observed phase transformation near GPa by X-ray diffraction that is associated with the molecular dissociation.