TY - JOUR
T1 - Oriented Gold Nanorods and Gold Nanorod Chains within Smectic Liquid Crystal Topological Defects
AU - Rožič, Brigita
AU - Fresnais, Jérôme
AU - Molinaro, Celine
AU - Calixte, Joseph
AU - Umadevi, Shivakumar
AU - Lau-Truong, Stephanie
AU - Felidj, Nordin
AU - Kraus, Tobias
AU - Charra, Fabrice
AU - Dupuis, Vincent
AU - Hegmann, Torsten
AU - Fiorini-Debuisschert, Celine
AU - Gallas, Bruno
AU - Lacaze, Emmanuelle
N1 - Publisher Copyright:
© 2017 American Chemical Society.
Copyright:
Copyright 2017 Elsevier B.V., All rights reserved.
PY - 2017/7/25
Y1 - 2017/7/25
N2 - We show that the use of oriented linear arrays of smectic A defects, the so-called smectic oily streaks, enables the orientation of gold nanorods (GNRs) for a large range of GNR diameters, ranging from 7 to 48 nm, and for various ligands. For the small GNRs it enables oriented end-to-end small chains of GNRs when the density is increased from around 2 GNRs/μm
2 to around 6 GNRs/μm
2. We have characterized the orientation of single GNRs by spectrophotometry and two-photon luminescence (TPL). A strongly anisotropic absorption of the composites and an on-off switching of GNR luminescence, both controlled by incident light polarization, are observed, revealing an orientation of the GNRs mostly parallel to the oily streaks. A more favorable trapping of GNRs by smectic dislocations with respect to ribbon-like defects is thus demonstrated. The dislocations appear to be localized at a specific localization, namely, the summit of rotating grain boundaries. Combining plasmonic absorption measurements, TPL measurements, and simulation of the plasmonic absorption, we show that the end-to-end GNR chains are both dimers and trimers, all parallel to each other, with a small gap between the coupled GNRs, on the order of 1.5 nm, thus associated with a large red-shift of 110 nm of the longitudinal plasmonic mode. A motion of the GNRs along the dislocations appears as a necessary ingredient for the formation of end-to-end GNR chains, the gap value being driven by the balance between the attracting van der Waals interactions and the steric repulsion between the GNRs and leading to interdigitation of the neighboring ligands. We thus obtain electromagnetic coupling of nanorods controlled by light polarization.
AB - We show that the use of oriented linear arrays of smectic A defects, the so-called smectic oily streaks, enables the orientation of gold nanorods (GNRs) for a large range of GNR diameters, ranging from 7 to 48 nm, and for various ligands. For the small GNRs it enables oriented end-to-end small chains of GNRs when the density is increased from around 2 GNRs/μm
2 to around 6 GNRs/μm
2. We have characterized the orientation of single GNRs by spectrophotometry and two-photon luminescence (TPL). A strongly anisotropic absorption of the composites and an on-off switching of GNR luminescence, both controlled by incident light polarization, are observed, revealing an orientation of the GNRs mostly parallel to the oily streaks. A more favorable trapping of GNRs by smectic dislocations with respect to ribbon-like defects is thus demonstrated. The dislocations appear to be localized at a specific localization, namely, the summit of rotating grain boundaries. Combining plasmonic absorption measurements, TPL measurements, and simulation of the plasmonic absorption, we show that the end-to-end GNR chains are both dimers and trimers, all parallel to each other, with a small gap between the coupled GNRs, on the order of 1.5 nm, thus associated with a large red-shift of 110 nm of the longitudinal plasmonic mode. A motion of the GNRs along the dislocations appears as a necessary ingredient for the formation of end-to-end GNR chains, the gap value being driven by the balance between the attracting van der Waals interactions and the steric repulsion between the GNRs and leading to interdigitation of the neighboring ligands. We thus obtain electromagnetic coupling of nanorods controlled by light polarization.
KW - end-to-end chains
KW - gold nanorods
KW - plasmon resonances
KW - smectic liquid crystal
KW - spectrophotometry
KW - two-photon luminescence microscopy
UR - http://www.scopus.com/inward/record.url?scp=85026324594&partnerID=8YFLogxK
U2 - 10.1021/acsnano.7b01132
DO - 10.1021/acsnano.7b01132
M3 - Article
SN - 1936-0851
VL - 11
SP - 6728
EP - 6738
JO - ACS nano
JF - ACS nano
IS - 7
ER -