Universal secondary relaxation of water in aqueous mixtures, in nano-confinement, and in hydrated proteins

From a large volume of experimental data of relaxation of water in various aqueous mixtures, in different forms of nano-confinement, and in two hydrated proteins, we show the presence of a secondary relaxation in all these systems that have similar characteristics. This ubiquitous secondary relaxation originates from water in the systems and is the analogue of the universal Johari-Goldstein secondary relaxation of glass-forming substances in general. Like all Johari-Goldstein secondary relaxation, this one from water bears an intimate and important relation to the primary structural relaxation, and hence it plays a fundamental role in glass transition or function of these water containing systems. © 2008 American Institute of Physics.