Interferometric Time-Resolved Probing of Acoustic Modes in Single Gold Nanospheres

TL;DR

This study uses interferometric time-resolved spectroscopy to investigate acoustic vibrations in single gold nanospheres, revealing their heterogeneity, damping, and shear modes at the nanoscale.

Contribution

It introduces a novel interferometric method for measuring mechanical vibrations in individual gold nanospheres, providing detailed insights into their acoustic properties.

Findings

Detection of high-contrast electronic signals in particles as small as 10 nm

Observation of mechanical vibrations with a 16 ps period in 50 nm particles

Identification of a lower-frequency shear mode

Abstract

We measure the transient absorption of single gold particles with a common-path interferometer. The prompt electronic part of the signal provides high-contrast images for diameters as small as 10 nm. Mechanical vibrations of single particles appear on a longer timescale (period of 16 ps for 50 nm diameter). They reveal the full heterogeneity of the ensemble, and the intrinsic damping of the vibration. We also observe a lower-frequency mode involving shear. Ultra-fast pump-probe spectroscopy of individual particles opens new insight into mechanical properties of nanometer-sized objects.