On the Photophysics of Electrochemically Generated Silver Nanoclusters: Spectroscopic and Theoretical Characterization

Ligand-free atomic silver nanoclusters (AgNCs) were successfully synthesized following the electrochemical procedure developed by Lopez-Quintela and col. (D. Buceta, N. Busto, G. Barone, J. M. Leal, F. Dominguez, L. J. Giovanetti, F. G. Requejo, B. Garcia and M. A. Lopez-Quintela, Angew. Chemie - Int. Ed., 2015, 54, 7612–7616) who have identified the presence of Ag2 and Ag3 AgNCs. The goal of this work was to get information on the photophysic of these AgNCs, which was achieved by combining information from excitation/emission matrix (EEM) and time resolved emission spectroscopy (TRES) along with DFT/TD-DFT calculations. This procedure allowed deconvolving the emission and excitation spectra of the AgNCs mixture, with further assignment of each transition and lifetimes associated to Ag2, Ag3+ and Ag42+ clusters. This deconvolution together with the theoretical calculations allowed suggesting for the first time the radiative and non-radiative excited state deactivation mechanism for these clusters.