Experimental determination of the energy difference between competing isomers of deposited, size-selected gold nanoclusters.

ABSTRACT: The equilibrium structures and dynamics of a nanoscale system are regulated by a complex potential energy surface (PES). This is a key target of theoretical calculations but experimentally elusive. We report the measurement of a key PES parameter for a model nanosystem: size-selected Au nanoclusters, soft-landed on amorphous silicon nitride supports. We obtain the energy difference between the most abundant structural isomers of magic number Au561 clusters, the decahedron and face-centred-cubic (fcc) structures, from the equilibrium proportions of the isomers. These are measured by atomic-resolution scanning transmission electron microscopy, with an ultra-stable heating stage, as a function of temperature (125-500?°C). At lower temperatures (20-125?°C) the behaviour is kinetic, exhibiting down conversion of metastable decahedra into fcc structures; the higher state is repopulated at higher temperatures in equilibrium. We find the decahedron is 0.040?±?0.020?eV higher in energy than the fcc isomer, providing a benchmark for the theoretical treatment of nanoparticles.

SUBMITTER: Foster DM 

PROVIDER: S-EPMC5882772 | biostudies-literature | 2018 Apr

REPOSITORIES: biostudies-literature