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Coalescence of cluster beam generated sub-2 nm bare Au nanoparticles and analysis of Au film growth parameters

Verrelli, Emanuele; Michelakaki, Irini; Boukos, Nikos; Kyriakou, Georgios; Tsoukalas, Dimitris

Authors

Irini Michelakaki

Nikos Boukos

Georgios Kyriakou

Dimitris Tsoukalas



Abstract

© 2017 by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim In this work is presented the growth model for Au films grown on a carbon substrate at room temperature by using as building blocks Au nanoparticles (NPs) with 1.4 nm mean size generated via remote cluster beam synthesis and soft landing on the substrate. The key results highlighted in this work are that 1) the deposited nanoparticles coalesce at substrate level in such a way that the film growth is 3D, 2) newly formed nanoparticles at substrate level are predominantly magic number clusters and 3) coalescensce takes place as soon as two neighboring nanopartciles come closer than a critical distance. The film growth was investigated by TEM as a function of Au load, in the range 0–1.2 μg/cm 2 . Two distinct regimes are identified: the “landing regime” and the “coalescence regime”. During the latter the film growth is 3D with a dynamic scaling exponent z of 2.13. Particular attention was devoted to the study of the evolution of the NP population from the moment they are generated with the cluster beam generator to the moment they land on the substrate and coalesce with other NPs. Our results show that 1) the NPs generated by the cluster beam are heterogeneous in size and are made by more than 95% by Au Magic numbers, mainly Au 20 and Au 55 and 2) kinetic processes (coalescence) at substrate level is capable of producing NPs populations made of larger Au magic numbers containing up to several thousands of Au atoms. Experimental and simulation results provide insight into the coalescence mechanism and provide strong evidence that the NPs coalesce when the nearest neighbor distance is below a critical mark. The critical distance is at its minimum 0.4-0.5 nm and it is still unclear whether it is constant or not although the best matching simulation results seem to point to a superlinear dependence from the NP size difference between two neighboring candidate coalescing NPs. The coalescence phenomenon investigated in this work pinpoints the unique self-organization properties of these small Au NPs in creating films with a stable edge-to-edge mean nearest neighbor distance of the order of 1.4 nm.

Citation

Verrelli, E., Michelakaki, I., Boukos, N., Kyriakou, G., & Tsoukalas, D. (2017). Coalescence of cluster beam generated sub-2 nm bare Au nanoparticles and analysis of Au film growth parameters. Annalen der Physik, 530(2), 1700256. https://doi.org/10.1002/andp.201700256

Journal Article Type Article
Acceptance Date Oct 25, 2017
Online Publication Date Nov 13, 2017
Publication Date Nov 13, 2017
Deposit Date Dec 8, 2017
Publicly Available Date Nov 14, 2018
Journal Annalen der Physik
Print ISSN 0003-3804
Electronic ISSN 1521-3889
Publisher Wiley
Peer Reviewed Peer Reviewed
Volume 530
Issue 2
Article Number ARTN 1700256
Pages 1700256
DOI https://doi.org/10.1002/andp.201700256
Keywords General Physics and Astronomy
Public URL https://hull-repository.worktribe.com/output/498624
Publisher URL http://onlinelibrary.wiley.com/wol1/doi/10.1002/andp.201700256/abstract
Copyright Statement This is the peer reviewed version of the following article: E. Verrelli, I. Michelakaki, N. Boukos, G. Kyriakou, D. Tsoukalas, ANNALEN DER PHYSIK 2017, which has been published in final form at https://doi.org/10.1002/andp.201700256. This article may be used for non-commercial purposes in accordance With Wiley Terms and Conditions for self-archiving.

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Copyright Statement
This is the peer reviewed version of the following article: E. Verrelli, I. Michelakaki, N. Boukos, G. Kyriakou, D. Tsoukalas, ANNALEN DER PHYSIK 2017, which has been published in final form at https://doi.org/10.1002/andp.201700256. This article may be used for non-commercial purposes in accordance With Wiley Terms and Conditions for self-archiving.







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