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The influence of molecular mobility on the properties of networks of gold nanoparticles and organic ligands

E. J. Devid ; P. N. Martinho ; Venkata Kamalakar Mutta (Institutionen för mikroteknologi och nanovetenskap, Kvantkomponentfysik) ; U. Prendergast ; C. Kubel ; T. Lemma ; J. F. Dayen ; T. E. Keyes ; B. Doudin ; M. Ruben ; S. J. van der Molen
Beilstein Journal of Nanotechnology (2190-4286). Vol. 5 (2014), p. 1664-1674.
[Artikel, refereegranskad vetenskaplig]

We prepare and investigate two-dimensional (2D) single-layer arrays and multilayered networks of gold nanoparticles derivatized with conjugated hetero-aromatic molecules, i.e., S-(4-{[2,6-bipyrazol-1-yl)pyrid-4-yl]ethynyl}phenyl) thiolate (herein S-BPP), as capping ligands. These structures are fabricated by a combination of self-assembly and microcontact printing techniques, and are characterized by electron microscopy, UV-visible spectroscopy and Raman spectroscopy. Selective binding of the S-BPP molecules to the gold nanoparticles through Au-S bonds is found, with no evidence for the formation of N-Au bonds between the pyridine or pyrazole groups of BPP and the gold surface. Subtle, but significant shifts with temperature of specific Raman S-BPP modes are also observed. We attribute these to dynamic changes in the orientation and/or increased mobility of the molecules on the gold nanoparticle facets. As for their conductance, the temperature-dependence for S-BPP networks differs significantly from standard alkanethiol-capped networks, especially above 220 K. Relating the latter two observations, we propose that dynamic changes in the molecular layers effectively lower the molecular tunnel barrier for BPP-based arrays at higher temperatures.

Nyckelord: aromatic capping ligands, gold nanoparticles, molecular charge transport, self-assembly, surface enhanced Raman spectroscopy

Denna post skapades 2014-12-08. Senast ändrad 2014-12-09.
CPL Pubid: 207681


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Institutioner (Chalmers)

Institutionen för mikroteknologi och nanovetenskap, Kvantkomponentfysik



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