Fractional hopping-type motion in columnar mesophase of semi-flexible rod-like particles

TL;DR

This study investigates the unique jump-like motion of semi-flexible rod-like particles in a columnar liquid crystal phase, revealing collective dynamics and defect-related movements through experiments and simulations.

Contribution

It uncovers the fractional, bimodal jump dynamics of particles in a columnar phase and links these to collective motion and defects, supported by experimental and simulation data.

Findings

Particles exhibit bimodal jump lengths at half and full particle sizes.

Full jumps are due to collective string-like movements.

Half jumps are associated with defect movements.

Abstract

We report on single-particle dynamics of strongly interacting filamentous fd virus particles in the liquid-crystalline columnar state in aqueous solution. From fluorescence microscopy we find that rare, discrete events take place, in which individual particles engage in sudden, jump-like motion along the main rod axis. The jump length distribution is bimodal and centered at half and full particle lengths. Our Brownian dynamics simulations of hard semi-flexible particles mimic our experiments, and indicate that full-length jumps must be due to collective dynamics in which particles move in string-like fashion in and between neighboring columns, while half jumps arise as a result of particles moving into defects. We find that the finite domain structure of the columnar phase strongly influences the observed dynamics.