Nanowerk June 23, 2023
Liquids induce electronic polarization and drive electric currents as they flow; electronic excitations, in turn, participate in hydrodynamic friction. Yet, the underlying solid–liquid interactions have been lacking a direct experimental probe. An international team of researchers (Germany, UK, Spain) heated graphene electron quasi-instantaneously by a visible excitation pulse and monitored the time evolution of the electronic temperature with a terahertz pulse. They observed that water accelerated the cooling of the graphene electrons, whereas other polar liquids leave the cooling dynamics largely unaffected. A quantum theory of solid–liquid heat transfer accounts for the water-specific cooling enhancement through a resonance between the graphene surface plasmon mode and the water charge fluctuations which allows for efficient energy transfer. According to the researchers their results provided direct experimental evidence of a solid–liquid interaction mediated by collective modes and support the theoretically proposed mechanism for quantum friction, and revealed a particularly large thermal boundary conductance for the water–graphene interface and suggest strategies for enhancing the thermal conductivity in graphene-based nanostructures… read more. Open Access TECHNICAL ARTICLEÂ
Heat transfer and friction at the solid–liquid interface. Credit: Nature Nanotechnology (2023)