The impact of endohedral atoms on the electronic and optical properties of Au25(SR)18 and Au38(SR)24

Abstract

An understanding of the rational modification of the optical properties of gold nanoparticles allows us to explore their versatility as molecular-sized materials. We show from theoretical relativistic calculations that such properties can be tuned efficiently by varying the architecture of the central core from endohedral to hollow structures in thiolate-protected clusters derived from two prototypical gold clusters, namely, Au₂₅(SR)₁₈ and Au₃₈(SR)₂₄. Our results estimate the feasible variation of the absorption spectrum driven by the modification of frontier levels due to the removal of the endohedral atom, leading to smaller gaps between occupied and low-lying unoccupied levels. This reveals a characteristic consequence for hollow counterparts given by a red-shift in energy of the optical properties. Hence, the formation of hollow derivatives can be a useful strategy for the fine-tuning of such properties. Future work will extend this observation to larger clusters, and allow gleaning knowledge of the electronic and optical properties in the case of higher order multilayer core nanoparticles.