Long lived acoustic vibrational modes of an embedded nanoparticle

TL;DR

This paper demonstrates through continuum elastic calculations that embedded nanoparticles can exhibit long-lived acoustic vibrational modes even with similar acoustic impedances to the surrounding matrix, and highlights how interface modeling can further reduce damping.

Contribution

It shows that long-lived vibrational modes are possible without impedance mismatch and introduces a multi-layer interface model to reduce damping further.

Findings

Long-lived vibrational modes occur despite similar impedances.

Continuum models can underestimate damping without detailed interface modeling.

Multi-layer interface models can enhance vibrational mode longevity.

Abstract

Classical continuum elastic calculations show that the acoustic vibrational modes of an embedded nanoparticle can be lightly damped even when the longitudinal plane wave acoustic impedances $Z_o=\rho v_L$ of the nanoparticle and the matrix are the same. It is not necessary for the matrix to be less dense or softer than the nanoparticle in order to have long lived vibrational modes. Continuum boundary conditions do not always accurately reflect the microscropic nature of the interface between nanoparticle and matrix, and a multi-layer model of the interface reveals the possibility of additional reduction of mode damping.