Reporting their results in the journal Nanotechnology, the researchers conducted a detailed study on the influence of surface modifications on luminescent silver clusters. These silver clusters are composed of 25 atoms capped with dihydrolipoic acid (DHLA) and show a distinct absorbance spectrum with several sharp transitions.

The silver clusters reveal a relatively broad deep red luminescence with a quantum yield of 5% combined with a remarkably long luminescence lifetime of ~3 µs at room temperature. Both pH and the presence of coordinating ligands influence the absorbance spectra and luminescence intensity.

These modifications were seen to induce a strong increase in luminescence intensity up to 45% quantum efficiency, and the team concluded that the surface coordination of the silver clusters has a strong influence on the material’s optical properties.

The researchers presented their work in the journal Nanotechnology.