Time-Domain Analysis for Fluid Damping of Acoustic Vibrations of Single Gold Nanorod in Water

Abstract

Acoustic vibrations of single gold nanorods with various widths and aspect ratios in water have been studied by the continuum finite element simulations in the time domain. As compared to the earlier analytical studies, lower quality factors of nanorods due to the fluid are obtained by the finite element calculations. Especially for the extensional mode, the quality factors predicted by the approximate analytical models can be several times our results. Nonmonotonic dependence of the quality factors of nanorods on the aspect ratio of nanorod is observed for both extensional and breathing modes. For a given aspect ratio, the extensional and breathing quality factors of nanorods are increased with the increase of the nanorod width. Further simulations with involving the heat transfer between the nanorod and the surrounding water show that while causing negligible changes in the frequencies of the nanorod, the variations in the local temperature and viscosity of the surrounding water lead to some, but not considerable, increase in the quality factors of the nanorod.