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Article

Acoustic Vibration Modes of Gold–Silver Core–Shell Nanoparticles

1
LuMIn, CNRS, ENS Paris-Saclay, CentraleSupélec, Université Paris-Saclay, 91190 Gif-sur-Yvette, France
2
Institut des Molécules et Matériaux du Mans, UMR 6283 CNRS, Le Mans Université, 72085 Le Mans, France
3
EuroFEL Support Laboratory (EFSL), Istituto di Struttura della Materia-CNR (ISM-CNR), 00100 Rome, Italy
4
LPS, CNRS, Université Paris-Saclay, 91405 Orsay, France
*
Author to whom correspondence should be addressed.
Academic Editor: Wei-Lung Tseng
Chemosensors 2022, 10(5), 193; https://doi.org/10.3390/chemosensors10050193
Received: 11 April 2022 / Revised: 11 May 2022 / Accepted: 16 May 2022 / Published: 20 May 2022
Bimetallic Au/Ag core–shell cuboid nanoparticles (NPs) exhibit a complex plasmonic response dominated by a dipolar longitudinal mode and higher-order transverse modes in the near-UV, which may be exploited for a range of applications. In this paper, we take advantage of the strong signature of these modes in the NP ultrafast transient optical response, measured by pump-probe transient absorption (TA) spectroscopy, to explore the NP vibrational landscape. The fast Fourier transform analysis of the TA dynamics reveals specific vibration modes in the frequency range 15–150 GHz, further studied by numerical simulations based on the finite element method. While bare Au nanorods exhibit extensional and breathing modes, the bimetallic NPs undergo more complex motions, involving the displacement of facets, edges and corners. The amplitude and frequency of these modes are shown to depend on the Ag shell thickness, as the silver load modifies the NP aspect ratio and mass. Moreover, the contributions of the vibrational modes to the experimental TA spectra are shown to vary with the probe laser wavelength at which the signal is monitored. Using the combined simulations of the NP elastic and optical properties, we elucidate this influence by analyzing the effect of the mechanisms involved in the acousto-plasmonic coupling. View Full-Text
Keywords: plasmonics; bimetallic nanoparticles; ultrafast; vibration modes; acousto-plasmonic coupling; transient absorption plasmonics; bimetallic nanoparticles; ultrafast; vibration modes; acousto-plasmonic coupling; transient absorption
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MDPI and ACS Style

Otomalo, T.O.; Di Mario, L.; Hamon, C.; Constantin, D.; Toschi, F.; Do, K.-V.; Juvé, V.; Ruello, P.; O’Keeffe, P.; Catone, D.; Paladini, A.; Palpant, B. Acoustic Vibration Modes of Gold–Silver Core–Shell Nanoparticles. Chemosensors 2022, 10, 193. https://doi.org/10.3390/chemosensors10050193

AMA Style

Otomalo TO, Di Mario L, Hamon C, Constantin D, Toschi F, Do K-V, Juvé V, Ruello P, O’Keeffe P, Catone D, Paladini A, Palpant B. Acoustic Vibration Modes of Gold–Silver Core–Shell Nanoparticles. Chemosensors. 2022; 10(5):193. https://doi.org/10.3390/chemosensors10050193

Chicago/Turabian Style

Otomalo, Tadele O., Lorenzo Di Mario, Cyrille Hamon, Doru Constantin, Francesco Toschi, Khanh-Van Do, Vincent Juvé, Pascal Ruello, Patrick O’Keeffe, Daniele Catone, Alessandra Paladini, and Bruno Palpant. 2022. "Acoustic Vibration Modes of Gold–Silver Core–Shell Nanoparticles" Chemosensors 10, no. 5: 193. https://doi.org/10.3390/chemosensors10050193

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