Charge Transfer in Low-energy Collisions of Protons with a Monolayer C60 Film Deposited on Cu(111)

V. QUINTERO RIASCOS; F. BONETTO; R. VIDAL; M. TACCA; E. C. GOLDBERG,

Conferencia; Autumn Meeting of the Brazilian Society of Physics 2020; 2020

Sociedad Brasilera de Física

Charge exchange processes in collisions between H+ projectiles and a monolayer C60film deposited on Cu(111) are experimentally and theoretically analyzed for a wide range of energies (2-8keV) in the low-energy regime. The negative, positive and total projectilescattered ion fractions are experimentally determined by using the low energy ionscattering (LEIS) technique. Two different collisional setups are studied for a fixedbackscattering angle of 135º: 45°/90° and 67.5°/67.5° incoming/exit angles, determinedwith respect to the target surface plane.Total ion fractions between 10% and 20% with comparable positive and negative scattered fractions are experimentally found in the whole energy range analyzed. A first-principles based theoretical model is used to describe the dynamic charge exchangeprocesses taking place in the experimental collisional situation. A good description of theexperimental results is obtained, especially for the 45°/90° collisional situation. This resultis a consequence of two factors: i) the final charge state is mostly defined in the exittrajectory of the projectile and ii) in the theoretical model a normal collision is assumed.Unlike to a three-layers thick C60 film deposited on cooper, the Cu substrate plays apreponderant role in the present problem. The substrate significantly alters: i) the total DOS of the monolayer, conferring metallic properties to the film, and ii) the local state density of the C atoms located close to the Cu(111) surface, which are potential scattering centers.