Acoustic Vibration Modes of Gold–Silver Core–Shell Nanoparticles

Chemosensors

Daniele Catone¹  Alessandra Paladini¹  Francesco Toschi¹  Patrick O’Keeffe¹  Lorenzo Di Mario¹  Pascal Ruello²  Vincent Juvé²  Cyrille Hamon³  Doru Constantin³  Tadele Orbula Otomalo⁴  Khanh-Van Do⁴  Bruno Palpant⁴ 

[1] EuroFEL Support Laboratory (EFSL), Istituto di Struttura della Materia-CNR (ISM-CNR), 00100 Rome, Italy;Institut des Molécules et Matériaux du Mans, UMR 6283 CNRS, Le Mans Université, 72085 Le Mans, France;LPS, CNRS, Université Paris-Saclay, 91405 Orsay, France;LuMIn, CNRS, ENS Paris-Saclay, CentraleSupélec, Université Paris-Saclay, 91190 Gif-sur-Yvette, France;

关键词: plasmonics;    bimetallic nanoparticles;    ultrafast;    vibration modes;    acousto-plasmonic coupling;    transient absorption;   

DOI  :  10.3390/chemosensors10050193

来源: DOAJ

【 摘 要 】

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.

【 授权许可】

Unknown