Sorbonne Universités, UPMC Université Paris 06, CNRS UMR 7588 , Institut des NanoSciences de Paris, F-75005 Paris, France.
Aix-Marseille Université, CNRS UMR 7334, IM2NP , F-13397 Marseille Cedex, France.
Nano Lett. 2016 Oct 12;16(10):6592-6598. doi: 10.1021/acs.nanolett.6b03260. Epub 2016 Sep 26.
The monochromatic and geometrically anisotropic acoustic field generated by 400 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 sides 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.
使用三维时间分辨飞秒泵浦探测实验，研究了简单放置在 10 μm 硅膜上的 400nm 和 120nm 直径的铜纳米线产生的单色谱且各向异性的声场。在硅衬底的两侧同时进行了两个泵浦探测时间分辨实验。在反射中，激发并探测了纳米线的第一径向呼吸模式。在透射中，观察到了纵波和切变波。纵波信号之后是与纳米线第一径向呼吸模式弛豫相关的单色谱分量。进行了有限差分时域（FDTD）模拟，精确地再现了衍射场。在声场中检测到了由纳米线的大纵横比引起的形状各向异性。因此，可以通过声学方法推断出底层纳米线的取向。
