title: Dynamics of individual single-walled carbon nanotubes in water by real-time visualization.
abstract: Individual single-walled carbon nanotubes (SWNTs) in aqueous suspension are visualized directly by fluorescence video microscopy. The fluorescent tagging is simple, biocompatible, and does not modify the SWNTs. The dynamics of individual SWNTs in water are observed and quantified for the first time. We measure the confined rotational diffusion coefficient and find it in reasonable agreement with predictions based on confined diffusion of dilute Brownian rods. We determine the critical concentration at which SWNTs in suspensions start interacting. By analyzing the fluctuating shape of SWNTs in the 3 to 5 microm range, we determine that their persistence length ranges between 32 and 174 microm, in agreement with theoretical estimates; thus, commonly available SWNTs in liquids can be considered as rigid Brownian rods in the absence of imposed external fields or self-attractive forces.
authors.affiliation: Department of Chemical and Biomolecular Engineering, Carbon Nanotechnology Laboratory, Center for Biological and Environmental Nanotechnology, The Smalley Institute for Nanoscale Science and Technology, Rice University, Houston, Texas 77005, USA.
authors.forename: Rajat
authors.initials: R
authors.lastname: Duggal
authors.forename: Matteo
authors.initials: M
authors.lastname: Pasquali