Resonant charge exchange in proton collisions with transition metal dichalcogenide 2D surfaces

Abstract

Resonant charge exchange in proton (H+) collisions with transition metal dichalcogenide (TMD) surfaces (MoSe2 and WSe2) are investigated through a quantum mechanical framework combining the extended Anderson model, Green-Keldysh formalism, and density functional theory (DFT). Significant differences in neutralization behavior emerge depending on whether the scatter center is a metallic atom (Mo/W) or a chalcogen atom (Se). We found that at incident energies above 3.5 keV, neutral charge fractions for H+ scattered by metallic atoms reach 60–75%, compared to 20–50 % achieve for Se. This difference arises from the distinct relative position of the projectile’sionization levels with the surface valence bands during the electron capture resonant process. Negative ion formation remains suppressed (<10 %) across all configurations, as affinity levels lie above the Fermi energy at critical distances. Core states, crucial in prior studies of heavier projectiles like Ne+ colliding with MoS2, exhibit negligible influence here due to the distinct energetics of H+ interactions. Theoretical comparisons between different approximations in the Coulomb repulsion parameter (U) confirm that correlation effects decrease with the projectile’s kinetic energy, with discrepancies emerging below 2 keV due to the extended projectilesurfaceinteraction times. These findings highlight the dominance of valence band hybridization in H+neutralization and emphasize the role of scatter-site electronic structure in charge transfer process efficiency. The results provide important insights for optimizing TMD-based technologies, from catalysis to ion-sensitive devices, where atomic-scale control over charge exchange is crucial.