Long-lived charge-separated states in ligand-stabilized silver clusters
KAUST DepartmentPhysical Sciences and Engineering (PSE) Division
KAUST Catalysis Center (KCC)
Materials Science and Engineering Program
KAUST Solar Center (KSC)
Functional Nanomaterials Lab (FuNL)
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AbstractRecently developed synthesis methods allow for the production of atomically monodisperse clusters of silver atoms stabilized in solution by aromatic thiol ligands, which exhibit intense absorption peaks throughout the visible and near-IR spectral regions. Here we investigated the time-dependent optical properties of these clusters. We observed two kinetic processes following ultrafast laser excitation of any of the absorption peaks: a rapid decay, with a time constant of 1 ps or less, and a slow decay, with a time constant that can be longer than 300 ns. Both time constants decrease as the polarity of the solvent increases, indicating that the two processes correspond to the formation and recombination, respectively, of a charge-separated state. The long lifetime of this state and the broad optical absorption spectrum mean that the ligand-stabilized silver clusters are promising materials for solar energy harvesting. © 2012 American Chemical Society.
SponsorsWe thank A. Demortiere for assistance with freeze-pump-thaw preparation and D. Gosztola and G. Wiederrecht for helpful discussions. Work at the Center for Nanoscale Materials was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract DE-AC02-06CH11357.
PublisherAmerican Chemical Society (ACS)