​Denis DAVID, Instituto de Física Universidade Federal da Bahia, Brasil

Christian GODET, Institut de Physique de Rennes, Université de Rennes 1, France

Andreas LINDBLAD and Fredrik JOHANSSON, Department of Physics and Astronomy, Uppsala University, Sweden

Host: Jerome JACKSON and Léon PETIT, STFC Scientific Computing Department, England

Monday 24th October @ 11:00-12:00

Application of the Photo-Electron Energy-Loss Spectroscopy to Black Phosphorus and Interpretation of its Energy-Loss Function using the Dielectric Function theory

Black phosphorus (BP) is a strongly anisotropic material potentially of great interest for applications in the fields of energy, sensing, and microelectronics. We have studied BP using X-ray Photoelectron Spectroscopy (XPS) at the synchrotron Soleil and applying the Photo-Electron Energy-Loss Spectroscopy (PEELS) method to determine its Energy-Loss Function (ELF). We found that the ELF depends on the incidence angle of the X-ray beam on the crystal and the orientation of the crystal relative to the plane of incidence. The standard dielectric model (SDM) for the bulk plasmon we initially applied was unable to correctly explain this behaviour. This can be due to the inadequate use of the optical dielectric function ε(q ⃗→0 ⃗,ω) as there is a momentum transferred from the photoelectron to the crystal. Thus, we are now calculating the dielectric function as a function of q ⃗ by the QS-GW method implemented in QUESTAAL. The first results we obtained show the widening of the ELF, as expected if compared with the experimental ELF determined by PEELS, and the appearance of a wide peak in the 10-eV region that the SDM does not produce. Work is going on.