Changes in the electronic structure of pyrite irradiated surfaces explored by UPS, ISS and DFT

G. RUANO; F. POMIRO; L. J. CRISTINA; E. A. ALBANESI; C. I. ZANDALAZINI; J. FERRÓN

Santa Fe

Conferencia; VI San Luis Conference on Surfaces, Interfaces and Catalysis; 2018

Pyrite has proven to be a versatile material. A commodity in the heavy industry, this inexpensive iron sulfide is, its bulk crystalline form (Pa6 group), an indirect-gap semiconductor. The fields of science in which its study is interesting ranges from biology; in regard to the origin of life , to solid state technology with the search of advanced semiconductors. Recently we have characterized by surface science techniques the interaction of noble gases ions (with kinetic energies in the keV range) with (100) natural surfaces of pyrite. We have find out that 4 keV He + ions induce a series of on-surface chemical reactions that lead to aggregates of iron. The so obtained nananoparticles (Fe-np) were had sizes and depth distributions highly dependent on the energy of the ions. In this work we analyze further the alteration focusing our attention in the electronic properties of the system, I. e. imbedded Fe-np in the semiconductor matrix, by a combination of ultraviolet photoemission spectroscopy (UPS) and density functional theory (DFT). With the additional light shed by ion scattering spectroscopy (ISS), which explores the atomic structure of the very surface, we have been able to assign the changes in the density of states (DOS) to both a change in atomic proportions (due to preferential sputtering) and to vacancies formation leading to iron agglomeration. Another interesting effect we report is the reversibility of the damage (S atomicity restitution and DOS structure) upon a thermal annealing of the system.