University of Jyväskylä

Chains of nanogold – forged with atomic precision

Researchers at the Nanoscience Center of the University of Jyväskylä in Finland have succeeded in producing short chains and rings of gold nanoparticles with unprecedented precision. The researchers used special kinds of nanoparticles with a well-defined structure and linked them together with molecular bridges. These structures – practically huge molecules – allow for extremely accurate studies of light-matter interaction in metallic nanostructures and plasmonics. The research was funded by the Academy of Finland.

Nanotechnology gives us tools to fabricate nanometre-sized particles where only a few hundred metal atoms form their core. New interesting properties emerge in this scale. For example, the light-matter interaction is extremely strong and catalytic activity increases. These properties have led to several applications, such as, chemical sensors and catalysts.

“Synthesis of nanoparticles usually yields a variety of sizes and shapes,” says lecturer, Dr Tanja Lahtinen. "The approach we use is exceptional in the sense that after purification we get only a single type of a nanoparticle. These nanoparticles have a specified number of each atom and the atoms are organised as a well-defined structure. It's essentially a single huge molecule with a core of gold."

The nanoparticles were linked with molecular bridges forming pairs, chains and rings of nanoparticles.

“When these kinds of nanostructures interact with light, electron clouds of the neighbouring metal cores become coupled,” explains researcher, Dr Eero Hulkko. The coupling significantly alters the electric field that molecules between the particles feel.

“Studying nanostructures that are well-defined at the atomic level allows us to combine experimental and computational methods in a seemless way,” adds Academy Research Fellow, Dr Lauri Lehtovaara. "We're aiming to understand light-matter interaction in linked metallic nanostructures at the quantum level. Deeper understanding is essential for development of novel plasmonic applications."

The research builds on a long-term multidispilinary collaboration at the Nanoscience Center of the University of Jyväskylä.

“I'm very happy that our dedicated efforts on studying monolayer protected clusters and their applications have created a unique multidisciplinary centre of excellence that is able to continuously publish high-impact science,” says Academy Professor Hannu Häkkinen, head of the Nanoscience Center.

In addition to the above persons, Karolina Sokołowska, Dr Tiia-Riikka Tero, Ville Saarnio, Dr Johan Lindgren and Professor Mika Pettersson contributed to the research. The research was published in the Nanoscale journal on 21 September 2016. Computational resources were supplied by CSC – IT Center for Science.

Article: Tanja Lahtinen, Eero Hulkko, Karolina Sokołowska, Tiia-Riikka Tero, Ville Saarnio, Johan Lindgren, Mika Pettersson, Hannu Häkkinen and Lauri Lehtovaara. “Covalently linked multimers of gold nanoclusters Au102(p-MBA)44 and Au∼250(p-MBA)n”. Nanoscale. DOI: 10.1039/c6nr05267c

http://pubs.rsc.org/en/content/articlelanding/2016/nr/c6nr05267c#!divAbstract

Further information:

Academy Research Fellow Lauri Lehtovaara, lauri.lehtovaara@jyu.fi, tel. +358 50 534 8642

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