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. Chem., Int. Ed., 2015,54, 7612-7616), who have identified the presence of Ag(2)and Ag3AgNCs. The goal of this work was to get information on the photophysics 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 AgNC mixture, with further assignment of each transition and lifetime associated to Ag-2, Ag(3)(+)and Ag(4)(2+)clusters. This deconvolution together with theoretical calculations allowed suggesting for the first time the radiative and non-radiative excited state deactivation mechanism for these clusters.