Damping of the Acoustic Vibrations of Individual Gold Nanoparticles

In this letter, the ultrafast vibrational dynamics of individual gold nanorings has been investigated by femtosecond transient absorption spectroscopy. Two acoustic vibration modes have been detected and identified. The influence of the mechanical coupling at the nanoparticle/substrate interface on the acoustic vibrations of the nano-objects is discussed. Moreover, by changing the environment of the nanoring, we provide a clear evidence of the impact of the surrounding medium on the damping of the acoustic vibrations. Such results are reported here for the first time on individual nanoparticles. This work points out a new sensing method based on the sensitivity of the acoustic vibration damping to the surrounding medium.