# Fast Diffusion of Long Guest Rods in a Lamellar Phase of Short Host Particles

## TL;DR

This study reveals that long guest rod-like particles diffuse faster than shorter host rods in liquid crystalline phases, due to size differences and the energy landscape, with implications for understanding particle mobility in ordered materials.

## Contribution

It demonstrates that long guest rods can diffuse faster than short host rods in lamellar phases, challenging traditional expectations about particle mobility in ordered systems.

## Key findings

- Long rods diffuse faster than short rods in smectic-A phase.
- Long guest particles remain mobile in smectic-B phase by creating voids.
- Diffusion speed is influenced by size and energy landscape interactions.

## Abstract

We investigate the dynamic behavior of long guest rod-like particles immersed in liquid crystalline phases formed by shorter host rods, tracking both guest and host particles by fluorescence microscopy. Counter-intuitively, we evidence that long rods diffuse faster than short rods forming the one-dimensional ordered smectic-A phase. This results from the larger and non-commensurate size of the guest particles as compared to the wavelength of the energy landscape set by the lamellar stack of liquid slabs. The long guest particles are also shown to be still mobile in the crystalline smectic-B phase, as they generate their own voids in the adjacent layers.