Molecular dynamics-based refinement of nanodiamond size measurements obtained with dynamic light scattering

TL;DR

This study uses molecular dynamics simulations to refine nanodiamond size measurements obtained via dynamic light scattering, especially for particles smaller than 3 nm where traditional models fail.

Contribution

The paper introduces a molecular dynamics-based method to improve size estimation of nanodiamonds from light scattering data, accounting for nanoscale effects.

Findings

Stokes-Einstein relation accurate for >3 nm particles

Diffusion coefficients need correction for <3 nm particles

Boundary conditions significantly affect diffusion predictions

Abstract

The determination of particle size by dynamic light scattering uses the Stokes-Einstein relation, which can break down for nanoscale objects. Here we employ a molecular dynamics simulation of fully solvated 1-5 nm carbon nanoparticles for the refinement of the experimental data obtained for nanodiamonds in water by using dynamic light scattering. We performed molecular dynamics simulations in differently sized boxes and calculated nanoparticles diffusion coefficients using the velocity autocorrelation function and mean-square displacement. We found that the predictions of the Stokes-Einstein relation are accurate for nanoparticles larger than 3 nm while for smaller nanoparticles the diffusion coefficient should be corrected and different boundary conditions should be taken into account.