![]() It's wonderful that robust spectroscopic experiments have now proved these phenomena. "My team predicted this kind of behaviour back in 2008–2009 when we saw big differences in the electronic structure of exactly these nanoclusters. "These experimental results go together very well with what our team has seen from computational simulations on these systems," said Professor Hannu Häkkinen, a co-author of the studies and the scientific director of the nanoscience centre. We've thus managed to bracket an important size region where this fundamentally interesting change in the behaviour takes place." This is exactly what we saw: the 102-gold atom cluster is a giant molecule showing even a transient magnetic state while the 144-gold atom cluster is already a metal. "The additional energy from light, absorbed by the metal-like clusters, transfers to the environment extremely rapidly, in about one hundred billionth of a second, while a molecule-like cluster is excited to a higher energy state and dissipates the energy into the environment with a rate that is at least 100 times slower. "Molecules behave drastically different from metals," said Professor Mika Pettersson, the principal investigator of the team conducting the experiments. The fundamentally different behaviour of these two differently sized gold nanoclusters was demonstrated by shining a laser light onto solution samples containing the clusters and by monitoring how energy dissipates from the clusters into the surrounding solvent. ![]() The researchers found that the smaller cluster, with up to 102 gold atoms, behaves like a giant molecule while the larger one, with at least 144 gold atoms, already behaves, in principle, like a macroscopic chunk of metal, but in nanosize. The clusters were synthesised by chemical methods incorporating a stabilising ligand layer on their surface. ![]() Two recent papers by the researchers at Jyväskylä demonstrate that the electronic properties of two different but still quite similar gold nanoclusters can be drastically different.
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