Role of Nanocrystal Symmetry in theCrossover Region from Molecular to Metallic Gold Nanoparticles

Abstract

There is a widespread interest to design ambient-stable gold nanoparticles with tailored physicochemical properties for applications in several areas such as plasmonics, nanomedicine, catalysis, biological imaging, sensing, and nanoelectronics. It has been known for a long time that optical response of gold nanoparticles changes drastically in a crossover region from 150 to 250 gold atoms, from a “molecule-like” to “metallic” behavior, but insufficient knowledge of atomic structures has precluded detailed computational studies on the underlying mechanisms. Here, we analyze the electronic structure and optical and chiroptical properties of recently reported gold nanoparticles of 144, 146, and 246 gold atoms that are made by wet chemistry methods and whose structures have been resolved to atomic precision. We demonstrate computationally how regrouping of the quantum states of valence electrons can affect drastically the optical properties of nanoparticles in the crossover-size region, by either generating a...