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Unraveling the atomic structure, ripening behavior, and electronic structure of supported Au20 clusters

Tijdschriftbijdrage - Tijdschriftartikel

The free-standing Au20 cluster has a unique tetrahedral shape and a large HOMO-LUMO (highest occupied molecular orbital-lowest unoccupied molecular orbital) gap of around 1.8 electron volts. The "magic" Au20 has been intensively used as a model system for understanding the catalytic and optical properties of gold nanoclusters. However, direct real-space ground-state characterization at the atomic scale is still lacking, and obtaining fundamental information about the corresponding structural, electronic, and dynamical properties, is challenging. Here, using cluster-beam deposition and low-temperature scanning tunneling microscopy, atom-resolved topographic images and electronic spectra of supported Au20 clusters are obtained. We demonstrate that individual size-selected Au20 on ultrathin NaCl films maintains its pyramidal structure and large HOMO-LUMO gap. At higher cluster coverages, we find sintering of the clusters via Smoluchowski ripening to Au20n agglomerates. The evolution of the electron density of states deduced from the spectra reveals gap reduction with increasing agglomerate size.
Tijdschrift: Science Advances
ISSN: 2375-2548
Issue: 1
Volume: 6
Jaar van publicatie:2020
BOF-keylabel:ja
IOF-keylabel:ja
BOF-publication weight:6
CSS-citation score:2
Auteurs:International
Authors from:Higher Education
Toegankelijkheid:Open