Atomistic simulation of the measurement of mechanical properties of gold nanorods by AFM

Abstract

Mechanical properties of nanoscale objects can be measured with an atomic force microscope (AFM) tip. However, the continuum models typically used to relate the force measured at a certain indentation depth to quantities such as the elastic modulus, may not be valid at such small scales, where the details of atomistic processes need to be taken into account. On the other hand, molecular dynamics (MD) simulations of nanoindentation, which can offer understanding at an atomistic level, are often performed on systems much smaller than the ones studied experimentally. Here, we present large scale MD simulations of the nanoindentation of single crystal and penta-twinned gold nanorod samples on a silicon substrate, with a spherical diamond AFM tip apex. Both the sample and tip sizes and geometries match commercially available products, potentially linking simulation and experiment. Different deformation mechanisms, involving the creation, migration and annihilation of dislocations are observed depending on the nanorod crystallographic structure and orientation. Using the Oliver-Pharr method, the Young’s moduli of the (100) terminated and (110) terminated single crystal nanorods, and the penta-twinned nanorod, have been determined to be 103 ± 2, 140 ± 4 and 108 ± 2 GPa, respectively, which is in good agreement with bending experiments performed on nanowires.

Synthesis and modelling of the mechanical properties of Ag, Au and Cu nanowires

“…Reactions for the synthesis involved the dissolution of the ionic Scheme 1. Synthesis, nanomechanical characterisation and simulation of coinage metal nanowires presented in this review (reprinted with permissions from [34] licensed under a Creative Commons Attribution 4.0 International License, with permission from [35] licensed under a Creative Commons Attribution-Non Commercial-Share Alike 3.0 Unported License, with permission from [36] Copyright (2011) American Chemical Society, with permissions from [37,38] under IOP Publishing [39,40], are licensed under a Creative Commons Attribution 4.0 International License, reproduced from [41] with permission from The Royal Society of Chemistry). [72].…”

Mapping stress inside living cells by atomic force microscopy in response to environmental stimuli

“…However, to extract correct stress (force per area) information from the collected f-d curves, one must know the correct analytical model to fit with indentation data and knowledge of the correct indenter tip shape [ 9 ]. For conventional specimen with flat surface and uniform composition, high-fidelity numerical simulation could be used to verify if a selected model and associated tip descriptors could reproduce experimental data [ 10 ]. However, in the case of a living cell, the surface topography is complex; internal structure and composition were both unknown.…”

Synthesis of gold nanorod/neodymium oxide yolk/shell composite with plasmon-enhanced near-infrared luminescence

“…32,33 Gold nanorod (AuNR) is a typical plasmonic structure used to enhance the uorescence of emitters, and it has tunable longitudinal surface plasmon resonance (LSPR) ranging from visible to near-infrared. [34][35][36] Since the excitation and emission frequencies of Nd are both in the near-infrared region, it is possible to design a resonance structure between the AuNR and Nd structures to achieve luminescence enhancement of Nd 3+ . 37 For obtaining luminescence enhancement, isolation between the plasmonic structure and the emitters is very important; silica, alumina, polymers, or DNAs have been applied to adjust the distance to obtain the largest enhancement.…”