| Abstract
| - The luminescence properties of chemically prepared gold nanoclusters, each composed of a 28-atom coreand a glutathione (GSH) adsorbate layer consisting of 16 molecules, were investigated. These clusters showa distinct absorption onset at 1.3 eV corresponding to the opening of an electronic gap within the conductionband (HOMO-LUMO gap). Here we report on the radiative properties of these molecular-like gold clusters.By using a combination of different detectors with sensitivities in the visible to the infrared (2.0−0.8 eV), abroad luminescence extending over this entire spectral range was observed. Our results further suggest thatthe luminescence can be separated into two bands with maxima around 1.5 and 1.15 eV indicating that radiativerecombination between the ground state and two distinctively different excited states takes place. The originof the observed luminescence bands is discussed using a solid state as well as a molecular model for theelectronic structure and relaxation of the clusters. The total quantum yield of the luminescence as measuredat ambient temperature was approximated to be about (3.5 ± 1.0) × 10-3.
|
