Dynamic Crossovers and Stepwise Solidification of Confined Water: A 2H NMR Study

H-2 NMR reveals two dynamic crossovers of supercooled water in nanoscopic (similar to 2 nm) confinement. At similar to 225 K, a dynamic crossover of liquid water is accompanied by formation of a fraction of solid water. Therefore, we do not attribute the effect to a liquid-liquid phase transition but rather to a change from bulk-like to interface-dominated dynamics. Moreover, we argue that the alpha process and beta process are observed in experiments above and below this temperature, respectively. Upon cooling through a dynamic crossover at similar to 175 K, the dynamics of the liquid fraction becomes anisotropic and localized, implying solidification of the corresponding water network, most probably, during a confinement-affected glass transition.