Absorption edges of black phosphorus: A comparative analysis

We have studied the excited states of black phosphorus through the analysis of K and L absorption edges of black phosphorus with energy-filtered transmission electron microscopy. Energy-loss spectra exhibit several peaks reflecting features in the density of conduction-band states at corresponding energies above the vacuum level. We have reproduced the experimental electron energy-loss near-edge structures by means of ab initio self-consistent real-space multiple-scattering theory. The comparison of the calculated symmetry-projected density of unoccupied states and electron energy loss spectra allowed us to assign the spectral features to transitions to specific electronic states.