Insights into the Synthesis Mechanism of Ag₂₉ Nanoclusters

The current understanding of the synthesis mechanisms of noble metal clusters is limited, in particular for Ag clusters. Here, we present a detailed investigation into the synthesis process of atomically monodisperse Ag₂₉ clusters, prepared via reduction of AgNO₃ in the presence of dithiolate ligands. Using optical spectroscopy, mass spectrometry, and X-ray spectroscopy, it was determined that the synthesis involves a rapid nucleation and growth to species with up to a few hundred Ag atoms. From these larger species, Ag₂₉ clusters are formed and their concentration increases steadily over time. Oxygen plays an important role in the etching of large particles to Ag₂₉. No other stable Ag cluster species are observed at any point during the synthesis.