Fig. 1.

Brillouin oscillations and localized acoustic vibrations of Au nanoplates. a Diagram of experimental geometry for Brillouin oscillation detection where the Au nanoplates were deposited on glass substrate. b Transient absorption trace of a Au nanoplate where Brillouin oscillations are observed. The blue line is the fitting curve to the experimental data with one oscillation term, see Eq. (1). The inset shows the isolated Brillouin oscillation component. c Fast Fourier transform (FFT) of the Brillouin oscillations. d Diagram of experimental geometry for localized acoustic vibration detection where the Au nanoplates were deposited on Lacey carbon film. e Transient absorption trace of acoustic vibrations. The blue line is the fitting curve to the experimental data with two oscillation terms. The inset shows the isolated acoustic vibrations. f FFT of the acoustic vibrations. The glass substrate and Lacey carbon film have thickness of 170 μm and 20 nm, respectively