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

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

Santa Fe, Argentina

Congreso; 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 anindirect-gap semiconductor. The fields of science in which its study isinteresting ranges from biology; in regard to the origin of life, to solidstate technology with the search of advanced semiconductors. Recently, we have characterized by surface science techniques theinteraction of noble gases ions (with kinetic energies in the keV range) with(100) natural surfaces of pyrite. We have found out that 4 keV He+ ions inducea series of on-surface chemical reactions that lead to aggregates of iron. Theso obtained nananoparticles (Fe-np) have sizes and depth distributions highlydependent on the energy of the ions. In this work we analyze further the alterationof the pyrite surface by ion bombardment focusing in the electronic propertiesof the system, i. e. imbedded Fe-np in the semiconductor matrix, by acombination of Ultraviolet Photoemission Spectroscopy (UPS) and DensityFunctional Theory (DFT). With the additional light shed by Ion ScatteringSpectroscopy (ISS), which explores the atomic structure of the very surface, wehave been able to assign the changes in the density of states (DOS) to both achange in atomic proportions (due to preferential sputtering) and to vacanciesformation leading to iron agglomeration. Another interesting effect we reporthere is the reversibility of the damage (S atomicity restitution and DOSstructure) upon a thermal annealing of the system.