金纳米粒子超晶格中的超快声等离子体
Ultrafast Acousto-Plasmonics in Gold Nanoparticles Superlattice
摘要：
我们报道了在等离子体金纳米粒子超晶格中GHz相干声学声子的产生和检测的研究。实验采用飞秒泵浦-探测的方法，通过超晶格的光学等离子体共振进行。我们的实验允许估计的集体弹性响应（声速），以及纳米接触的弹性刚度的估计。看起来，光诱导相干声学声子脉冲具有约45 nm的典型深度空间延伸，其大约是金中光学趋肤深度的4倍。瞬态光学反射率的建模表明，声子产生的机制是通过超快加热的体积等离子体激元的光激发的辅助下，实现的。这些结果表明，它是如何可能映射的光子-电子-声子相互作用的亚波长纳米结构。
英文摘要：
We report the investigation of the generation and detection of GHz coherent acoustic phonons in plasmonic gold nanoparticles superlattices (NPS). The experiments have been performed from an optical femtosecond pump-probe scheme across the optical plasmon resonance of the superlattice. Our experiments allow to estimate the collective elastic response (sound velocity) of the NPS as well as an estimate of the nano-contact elastic stiffness. It appears that the light-induced coherent acoustic phonon pulse has a typical in-depth spatial extension of about 45 nm which is roughly 4 times the optical skin depth in gold. The modeling of the transient optical reflectivity indicates that the mechanism of phonon generation is achieved through ultrafast heating of the NPS assisted by light excitation of the volume plasmon. These results demonstrate how it is possible to map the photon-electron-phonon interaction in subwavelength nanostructures.
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