_Seminar

Hydroelectrons in water-filled carbon nanotubes driven by nonequilibrium carriers

Water confined in nanoscale channels serves as a prototypical system in nanofluidics, where interfacial interactions and geometric confinement fundamentally reshape molecular structure, dielectric response, and transport behavior. Carbon nanotubes provide an ideal platform for such studies due to their well-defined one-dimensional geometry. Here, we achieve precise filling of water inside single-walled carbon nanotubes with diameters down to ~0.4 nm via capillary condensation, enabling controlled investigation of deeply confined water.
Using terahertz spectroscopy, we observe a pronounced suppression of photoconductivity in carbon nanotubes upon water filling, indicating strong coupling between charge carriers and confined water. We further identify the emergence of hydroelectronic states at frequencies resonant with the librational modes of confined water. Analysis of ultrafast axial carrier motion reveals that transient electronic transport can promote water flow within the nanotube, suggesting a microscopic mechanism underlying the anomalously high flow rates in nanoconfined systems. These results establish a direct coupling between ultrafast electronic dynamics and nanofluidic transport and point to optoelectronic excitation as a route to control water behavior at the nanoscale.

Host: Dr. Markus Huber