Surface plasmon resonance-induced stiffening of silver nanowires.

Xue Ben,Harold S Park

doi:10.1038/srep10574

Abstract

We report the results of a computational, atomistic electrodynamics study of the effects of electromagnetic waves on the mechanical properties, and specifically the Young’s modulus of silver nanowires. We find that the Young’s modulus of the nanowires is strongly dependent on the optical excitation energy, with a peak enhancement occurring at the localized surface plasmon resonance frequency. When the nanowire is excited at the plasmon resonance frequency, the Young’s modulus is found to increase linearly with increasing nanowire aspect ratio, with a stiffening of nearly 15% for a 2 nm cross section silver nanowire with an aspect ratio of 3.5. Furthermore, our results suggest that this plasmon resonance-induced stiffening is stronger for larger diameter nanowires for a given aspect ratio. Our study demonstrates a novel approach to actively tailoring and enhancing the mechanical properties of metal nanowires.

Highlights

FCC metal nanostructures such as gold and silver exhibit localized surface plasmon resonance (LSPR), which is a unique optical response that occurs upon interaction with incident electromagnetic waves such as light at specific wavelengths[1,2,3,4,5,6] within the visible spectrum
By coupling atomistic electrodynamic computational techniques for the optical properties[37] and standard molecular statics for the mechanical properties[38,39], the strong effect of LSPR on the Young’s modulus of silver nanowires
We demonstrate that the Young’s modulus of silver nanowires is sensitive to the LSPR wavelength, and shows a substantial increase when silver is excited at the LSPR wavelength

Summary

Computational Methodology

When an electromagnetic field interacts with a silver nanowire, a frequency-dependent dipolar response is excited in each atom These induced dipoles result in an optical force that will either augment or oppose any mechanical force that is applied to probe the mechanical properties of the nanostructure[40,41]. Nanowires with increasing axial length (for a fixed cross sectional size) exhibit a stronger reduction of the compressive strain, which results in a larger change in the Young’s modulus. This implies that it is more effective to make the nanowire stiffer by increasing its axial length than by decreasing the cross sectional size

Conclusions

Findings

Additional Information