Ultrafast phonon and hydrated electron processes of water droplets.^[32,33] Lifetime of (a) the D–O phonons in the droplet skin compared with that in the NaBr/H₂O solutions^[33] and the lifetime of (b) electron hydrated by the sized (H₂O)_n and (D₂O)_n clusters and their skins.^[32] Insets in (a) illustrate the ionic hydration and the core-shelled water droplet. The skin supersolidity hinders the motion dynamics of both phonons and nonbonding electrons.^[55]