Self-diffusion of rod-like viruses in the nematic phase

We measure the self-diffusion of colloidal rod-like virus f d in an isotropic and nematic phase. A low-volume fraction of viruses are labelled with a fluorescent dye and dissolved in a background of unlabelled rods. The trajectories of individual rods are visualized using fluorescence microscopy from which the diffusion constant is extracted. The diffusion parallel (D || ) and perpendicular (D ⊥ ) to the nematic director is measured. The ratio (D || /D ⊥ ) increases monotonically with increasing virus concentration. Crossing the isotropic-nematic phase boundary results in increase of D || and decrease of D ⊥ when compared to the diffusion in the isotropic phase (D iso ). © EDP Sciences.