Efficient measurement of length distribution of 1D nanoparticles in solution via optical polarimetry

Published

December 1, 2025

Author(s)

Jeffrey Fagan, Richard Castellano, Da-Chi Yang, Sei Jin Park, Pavel Shapturenka, Robert Praino, Francesco Fornasiero, Jerry Shan

Abstract

The efficient measurement of the length distribution of nanotubes, nanowires, and other 1D nanoparticles in solution is important to enable their incorporation into materials and devices, and to optimize their processing for properties of interest, such as thermal/electrical conductivity or mechanical strength, in suspensions and composites. We report an electric-field- (E-field-) assisted optical-polarimetry technique to measure the length distribution of ensembles of high-aspect-ratio particles in dilute suspension. The degree of alignment of polarizable 1D particles suspended in a fluid under Brownian motion explicitly depends on the E-field strength and the particle length. We show that it is possible to extract the length distribution of 1D nanoparticles suspended in an insulating fluid by applying a range of E-fields and using optical polarimetry to measure the corresponding alignment-order parameter. Notably, the method is relatively insensitive to the diameter of the 1D particles, which can be poorly known or vary within a sample. The technique is validated with silver nanowires and carbon nanotubes of known lengths, as well as polymer-depletion-length-separated (PDLS) single-wall-carbon-nanotube (SWCNT) samples with length distributions independently measured with analytical ultracentrifugation. Finally, we demonstrate the ability of the optical-polarimetry technique to quantify changes in length distribution of ultra-narrow, sub-nanometer-diameter SWCNT samples under different types and durations of ultrasonication. Within its range of applicability (polarizable 1D nanoparticles in the 0.5 – 15 μm length range), the E-field-assisted optical-polarimetry method is a particularly efficient and accurate method to measure the length distribution of nanowires and nanotubes in suspension.

Citation

ACS Nano

Volume

19

Pub Type

Journals

Download Paper

https://doi.org/10.1021/acsnano.5c14994

Local Download

Keywords

nanotube, 1D, length, polarimetry

Citation

Fagan, J. , Castellano, R. , Yang, D. , Park, S. , Shapturenka, P. , Praino, R. , Fornasiero, F. and Shan, J. (2025), Efficient measurement of length distribution of 1D nanoparticles in solution via optical polarimetry, ACS Nano, [online], https://doi.org/10.1021/acsnano.5c14994, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=960545 (Accessed April 9, 2026)