Highlighting a deep impact of wetting on solid dynamics
Résumé
It is generally accepted that the liquid-solid boundary has no effects on bulk properties of solids. We show here that this view might be antiquated, at least for hydrophilic surfaces. While the influence of the confinement or of a wall vicinity has been widely studied on liquid properties [1,2], investigations of liquid induced effects on the solid are nonexistent to our knowledge.This experimental study [4] reveals that the liquid affects the solid dynamics. For that, high-energy Inelastic X-ray Scattering (IXS) at ESRF at ambient temperature and pressure was used to probe the acoustic phonon distribution of α-Al 2 O 3 (wetted on the cplane), a monocrystal known for its high interaction with liquid water by the way of hydroxylation [3], up to 300µm. The results show a significant shift of acoustic phonon energy towards higher energies, and thus a hardening of the solid substrate, due to wetting. This hardening takes place kinetically and is observable down to 150µm depth. Moreover, a relaxation of internal stresses due to wetting is identified down to 300µm depth. These findings indicate a strong long-range wetting impact, leading to dynamic changes in the solid that correspond to changes in macroscopic quantities. This novel effect would pave the way for numerous scientific and technological developments