Noll F, Krauß N, Gusev V, Dekorsy T, Hettich M
Department of Physics, University of Konstanz, 78464 Konstanz, Germany.
Research Center for Non-Destructive Testing GmbH (RECENDT), Altenbergerstr. 69, 4040 Linz, Austria.
Photoacoustics. 2023 Feb 23;30:100464. doi: 10.1016/j.pacs.2023.100464. eCollection 2023 Apr.
Longitudinal acoustic modes in planar thin gold films are excited and detected by a combination of ultrafast pump-probe photoacoustic spectroscopy and a surface plasmon resonance (SPR) technique. The resulting high sensitivity allows the detection of acoustic modes up to the 7th harmonic (258 GHz) with sub-pm amplitude sensing capabilities. This makes a comparison of damping times of individual modes possible. Further, the dynamics of the real and imaginary part of the dielectric function and the film's thickness variation are separated by using the dependence of the amplitudes of the acoustic modes on the detection angle and the surface plasmon resonance. We find that longitudinal acoustic modes in the gold films mainly affect the real part of the dielectric function and highlight the importance to consider thickness related effects in acousto-plasmonic sensing.
通过超快泵浦 - 探测光声光谱和表面等离子体共振（SPR）技术的结合，在平面薄金膜中激发并检测纵向声学模式。由此产生的高灵敏度使得能够检测高达七次谐波（258GHz）的声学模式，并具有亚皮米幅度传感能力。这使得比较各个模式的阻尼时间成为可能。此外，利用声学模式幅度对检测角度和表面等离子体共振的依赖性，分离了介电函数实部和虚部的动力学以及薄膜厚度变化。我们发现金膜中的纵向声学模式主要影响介电函数的实部，并强调了在声等离子体传感中考虑厚度相关效应的重要性。
