College of Electronic Science and Technology, Shenzhen University , Shenzhen 518060, P. R. China.
Department of Chemistry and Biochemistry, University of Notre Dame , Notre Dame, Indiana 46556, United States.
ACS Nano. 2017 Aug 22;11(8):8064-8071. doi: 10.1021/acsnano.7b02703. Epub 2017 Jun 29.
Brillouin oscillations, which are GHz frequency waves that arise from the interaction of light with acoustic waves, are experiencing increasing applications in biology and materials science. They provide information about the speed of sound and refractive index of the material they propagate in, and have recently been used in imaging applications. In the current study, Brillouin oscillations are observed through ultrafast transient reflectivity measurements using chemically synthesized Au nanoplates as opto-acoustic transducers. The Au nanoplates are semitransparent, which allows the Brillouin oscillations to be observed from material on both sides of the plate. The measured frequencies are consistent with the values expected from the speeds of sound in the different materials, however, the attenuation constants are much larger than those reported in previous studies. The increased damping is attributed to diffraction of the acoustic wave as it propagates away from the excitation region. This effect is more significant for experiments with high numerical aperture objectives. These results are important for understanding the relationship between frequency and spatial resolution in Brillouin oscillation microscopy.
布里渊振荡是一种 GHz 频率的波，它是由光与声波相互作用产生的，在生物学和材料科学领域的应用越来越广泛。它们提供了关于传播介质中声波速度和折射率的信息，最近已被用于成像应用。在当前的研究中，通过使用化学合成的 Au 纳米板作为光声换能器进行超快瞬态反射率测量来观察布里渊振荡。Au 纳米板是半透明的，这使得可以从板两侧的材料观察到布里渊振荡。测量的频率与不同材料中预期的声速值一致，但是，衰减常数比以前的研究报告的大得多。增加的阻尼归因于声波在远离激励区域传播时的衍射。对于具有高数值孔径物镜的实验，这种影响更为显著。这些结果对于理解布里渊振荡显微镜中频率与空间分辨率之间的关系非常重要。
