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Related Experiment Video

Updated: May 3, 2026

Light-driven Molecular Motors on Surfaces for Single Molecular Imaging

Light-driven Molecular Motors on Surfaces for Single Molecular Imaging

Published on: March 13, 2019

A surface-bound molecule that undergoes optically biased Brownian rotation.

James A Hutchison¹, Hiroshi Uji-i², Ania Deres²

¹1] Laboratory for Photochemistry and Spectroscopy, Katholieke Universiteit Leuven, Heverlee 3001 Belgium [2] ISIS & icFRC, Université de Strasbourg & CNRS UMR 7006, Strasbourg 67000, France.

Nature Nanotechnology

|January 21, 2014

Summary

Researchers visualized molecular rotor motion, observing a transition from hindered to free rotation. Light polarization biased random motion via a fluctuating-friction mechanism, not optical torque.

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Published on: February 4, 2017

Area of Science:

Nanotechnology
Molecular Machines
Brownian Motion

Background:

Developing nanoscale machines with macroscopic analogies is a key goal.
Friction, not inertia, dominates nanoscale environments.
Ratchet mechanisms can bias Brownian motion for directed diffusion.

Purpose of the Study:

To visualize surface-bound molecular rotor motion.
To investigate the transition between hindered and free Brownian rotation.
To explore light polarization's effect on molecular rotor dynamics.

Main Methods:

Defocused fluorescence imaging was used to visualize molecular rotor movements.
Medium viscosity was tuned to observe rotational transitions.
Analysis of light polarization effects on rotor dynamics.

Main Results:

The transition from hindered to free Brownian rotation was observed by altering medium viscosity.
Light polarization biased random molecular rotor rotations.
This bias was attributed to a fluctuating-friction mechanism, not direct optical torque.

Conclusions:

Photoexcitation of molecular rotors significantly inhibits their diffusion rate.
Fluctuating friction, influenced by light, can bias nanoscale rotational motion.
This provides a novel mechanism for controlling molecular machines.