After the initial coherent coupling of an incident electromagnetic wave with the electron gas of a metallic particle, energy dissipation involves a complex sequence of processes that eventually leads to heat release in the surroundings. The thermalization of the electron gas, the electron-lattice thermalization, the vibrational dynamics and the thermal diffusion have been first investigated by ultrafast spectroscopy on metallic films and then on large collections of nanoparticles. In the case of metallic films, it has been shown that the investigation of the damping of the acoustic vibrations by picosecond ultrasonics brings important information about the mechanical coupling at the interface between two media but accessing similar information on nanosized metal particles is challenging. Indeed, in optical spectroscopy experiments performed on large ensembles of particles, nano-objects with different sizes and shapes contribute to the detected signal. This yields an additional inhomogeneous contribution to the measured damping, which demands either sophisticated modelling or highly monodisperse samples. This limitation can be overcome thanks to the development of ultrafast optical spectroscopy experiments addressing individual metallic nano-objects. We have developed in CEMES an experimental set-up capable of resolving the acoustic vibrations of individual nano-objects and investigate their mechanical coupling with the environment.
Contact: Arnaud Arbouet
References:
From patterned optical near-fields to high symmetry acoustic vibrations in gold crystalline platelets J. Fedou, S. Viarbitskaya, R. Marty, J. Sharma, V. Paillard, E. Dujardin, and A. Arbouet Phys. Chem. Chem. Phys., 15, 4205-4213, 2013 (invited contribution) - web
Damping of the Acoustic Vibrations of Individual Gold Nanoparticles R. Marty; A. Arbouet; C. Girard ; A. Mlayah; V. Paillard; V. K. Lin; S. L. Teo; S. Tripathy Nanoletters, 11 (8), 3301-3306, 2011 – web Highlight in Phys.org and ScienceDaily