Ligand-protectedAuclusters are non-bleaching fluorescence markers in bio- and medical applications. Here we showthat their fluorescence can be an intrinsic property of the Au cluster itself.We find a very intense and sharp fluorescence peak located at lambda= 739.2 nm (1.68 eV) for Au20 clusters in a Ne matrix held at 6 K. The fluorescence reflects the Highest Occupied Molecular Orbital-Lowest Unoccupied Molecular Orbital (HOMO-LUMO) diabatic bandgap of the cluster. Au20 shows a very rich absorption fine structure reminiscent of well defined molecule-like quantum levels. These levels are resolved since Au20 has only one stable isomer (tetrahedral); therefore our sample is mono-disperse in cluster size and conformation. Density-functional theory (DFT) and time-dependent DFT calculations clarify the nature of optical absorption and predict both main absorption peaks and intrinsic fluorescence in fair agreement with experiment.

Intense fluorescence of Au20

STENER, MAURO;FORTUNELLI, ALESSANDRO;
2017

Abstract

Ligand-protectedAuclusters are non-bleaching fluorescence markers in bio- and medical applications. Here we showthat their fluorescence can be an intrinsic property of the Au cluster itself.We find a very intense and sharp fluorescence peak located at lambda= 739.2 nm (1.68 eV) for Au20 clusters in a Ne matrix held at 6 K. The fluorescence reflects the Highest Occupied Molecular Orbital-Lowest Unoccupied Molecular Orbital (HOMO-LUMO) diabatic bandgap of the cluster. Au20 shows a very rich absorption fine structure reminiscent of well defined molecule-like quantum levels. These levels are resolved since Au20 has only one stable isomer (tetrahedral); therefore our sample is mono-disperse in cluster size and conformation. Density-functional theory (DFT) and time-dependent DFT calculations clarify the nature of optical absorption and predict both main absorption peaks and intrinsic fluorescence in fair agreement with experiment.
15-ago-2017
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http://aip.scitation.org/doi/10.1063/1.4996687
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11368/2910744
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