Light Cuts Carbon Nanotube Diffusion by 50% in Water as Exciton-Water Quantum Friction Emerges
Updated
Updated · Nature.com · Jun 10
Light Cuts Carbon Nanotube Diffusion by 50% in Water as Exciton-Water Quantum Friction Emerges
1 articles · Updated · Nature.com · Jun 10
Summary
Single-walled carbon nanotubes in water slowed their Brownian diffusion by about 50% as near-infrared light excitation increased, giving direct experimental evidence of light-induced quantum friction.
THz pump-probe data tied the slowdown to exciton-water coupling, showing an immediate signal near 30 cm−1 followed by a slower heating-like response above 100 ps in water’s hydrogen-bond network.
Chemical tuning reinforced the mechanism: molecules that brightened nanotube fluorescence slowed diffusion, while quenchers sped it up, shifting diffusion constants by up to a factor of 2.
Exciton mobility proved crucial, because nanotubes with sp3 quantum defects that localize excitons lost the light-dependent effect, and heavier shielding by surface coronas also weakened it.
Molecular dynamics simulations supported the experiments, finding polarizable excited nanotubes had much higher friction and more than 30% lower diffusion, suggesting a route to control nanoscale motion, nanofluidics and microswimmers.
If light can create friction to stop nanoparticles, can it also be used to create light-powered nano-engines?
Could light now steer nanorobots through our bloodstream to precisely target and fight diseases?
Light Slows Nanotube Diffusion by 50%: Quantum Friction Unveiled at the Nanoscale
Overview
In 2026, scientists made a major breakthrough by discovering that shining light on single-walled carbon nanotubes (SWCNTs) suspended in water can slow their movement by up to 50%. This finding, published in Nature, marks a pivotal moment in our understanding of nanoscale dynamics. By controlling the diffusion of SWCNTs with light, researchers have opened new possibilities for manipulating nanomaterials in ways that could benefit targeted drug delivery and advanced material fabrication. This discovery not only deepens our knowledge of how light interacts with nanomaterials but also paves the way for innovative applications in nanotechnology.