The mysterious movement of water molecules
In the course of their research, the team used a combination of a new experimental method called helium spin-echo spectroscopy and theoretical calculations. Helium spin-echo spectroscopy uses very low-energy helium atoms that allow isolated water molecules to be observed without influencing their motion in the process. The researchers discovered that water molecules behave completely differently on bismuth telluride compared with those on conventional metals. On such metals, attractive interactions between water molecules can be observed, leading to accumulations in the form of films. But the opposite is the case with topological insulators: the water molecules repel one another and remain isolated on the surface.
Bismuth telluride appears to be impervious to water, which is an advantage for applications exposed to typical environmental conditions. Plans are in place for further experiments on similarly structured surfaces, which are intended to clarify whether the movement of water molecules is attributable to specific features of the surface in question.