Spectroscopy of vibrational modes in metal nanoshells

TL;DR

This paper investigates the vibrational modes of metal nanoshells, revealing how their unique structure affects vibrational energy spectra and damping, with implications for optical and thermal properties.

Contribution

It provides the first detailed calculation of vibrational spectra and damping for metal nanoshells, highlighting differences from solid nanoparticles.

Findings

Fundamental breathing mode has larger oscillator strength in nanoshells.

Very thin nanoshells exhibit overdamped fundamental modes.

Energy transfer to surrounding medium affects damping in thin nanoshells.

Abstract

We study the spectrum of vibrational modes in metal nanoparticles with a dielectric core. Vibrational modes are excited by the rapid heating of the particle lattice that takes place after laser excitation, and can be monitored by means of pump-probe spectroscopy as coherent oscillations of transient optical spectra. In nanoshells, the presence of two metal surfaces results in a substantially different energy spectrum of acoustic vibrations than for solid particles. We calculated the energy spectrum as well as the damping of nanoshell vibrational modes. The oscillator strength of fundamental breathing mode is larger than that in solid nanoparticles. At the same time, in very thin nanoshells, the fundamental mode is overdamped due to instantaneous energy transfer to the surrounding medium.