Spatiotemporal Imaging of the Acoustic Field Emitted by a Single Copper Nanowire

Cyril Jean (1) , Laurent Belliard (1) , Thomas W. Cornelius (2) , Olivier Thomas (2) , Yan Pennec (3) , Marco Cassinelli (4) , Maria Eugenia Toimil-Molares (4) , Bernard Perrin (1, 5)

1 INSP - Institut des Nanosciences de Paris
2 IM2NP - Institut des Matériaux, de Microélectronique et des Nanosciences de Provence
3 IEMN - Institut d’Électronique, de Microélectronique et de Nanotechnologie - UMR 8520
4 GSI - Helmholtz zentrum für Schwerionenforschung GmbH
5 INSP-E3 - Acoustique pour les nanosciences

The monochromatic and geometrically anisotropic acoustic field generated by 400 nm and 120 nm diameter copper nanowires simply dropped on a 10 µm silicon membrane is investigated in transmission using three-dimensional time-resolved femtosecond pump-probe experiments. Two pump-probe time-resolved experiments are carried out at the same time on both side of the silicon substrate. In reflection, the first radial breathing mode of the nanowire is excited and detected. In transmission, the longitudinal and shear waves are observed. The longitudinal signal is followed by a monochromatic component associated with the relaxation of the nanowire's first radial breathing mode. Finite Difference Time Domain (FDTD) simulations are performed and accurately reproduce the diffracted field. A shape anisotropy resulting from the large aspect ratio of the nanowire is detected in the acoustic field. The orientation of the underlying nanowires is thus acoustically deduced.

Mots clés: acoustic transducers; sub optical diffraction limited acoustic; nanowires; ultrafast pump-probe spectroscopy; acoustic phonons

Domaines: Systèmes mésoscopiques et effet Hall quantique [cond-mat.mes-hall]

Cyril Jean, Laurent Belliard, Thomas W. Cornelius, Olivier Thomas, Yan Pennec, et al.. Spatiotemporal Imaging of the Acoustic Field Emitted by a Single Copper Nanowire. Nano Letters, 2016, 16 (10), pp.6592-6598. ⟨10.1021/acs.nanolett.6b03260⟩. ⟨hal-01370656v2⟩