A novel experimental platform to monitor solid/water interfaces under freeze–thaw cycles

We design and implement an original experimental platform resting on Atomic Force Microscopy (AFM) to capture nanoscale insights into key characteristics of solid/water interfaces subject to freeze-thaw conditions. The work is motivated by the observation that freezing and thawing underpin a variety of processes in the context of, e.g., climate and material sciences or cryobiology. Despite their key role, fundamental processes driving freezing and thawing are still elusive and their direct documentation is still challenging. This primarily stems from operational difficulties in replicating these processes under laboratory conditions, as well as constraints of current technology in matching temporal and spatial scales at which these phenomena take place. Here, we propose an experimental strategy to control freezing at solid/water interfaces while maintaining the bulk water as liquid. Our platform favors operational simplicity and can be integrated with any tip-scanning AFM. The strength of our set-up is assessed upon experiments performed on Highly Oriented Pyrolytic Graphite (HOPG) as a model substrate.