title: The glass transition of water, based on hyperquenching experiments.
abstract: The glass transition temperature (Tg) in water is still uncertain, with conflicting values reported in the literature. As with other hyperquenched glasses, water exhibits a large relaxation exotherm on reheating at the normal rate of 10 kelvin (K) per minute. This release of heat indicates the transformation of a high enthalpy state to a lower one found in slow-cooled glasses. When the exotherm temperature is scaled by Tg, the good glass-formers show a common pattern. However, for hyperquenched water, when this analysis is performed using the commonly accepted Tg = 136 K, its behavior appears completely different, but this should not be the case because enthalpy relaxation is fundamental to the calorimetric glass transition. With Tg = 165 +/- 5 K, normal behavior is restored in comparison with other hyperquenched glasses and with the binary solution behavior of network-former systems (H2O, ZnCl2, or BeF2 plus a second component). This revised value has relevance to the understanding of water- biomolecule interactions.
authors.affiliation: Department of Chemistry and Biochemistry, Arizona State University, Tempe, AZ 85287, USA.
authors.forename: V
authors.initials: V
authors.lastname: Velikov
authors.forename: S
authors.initials: S
authors.lastname: Borick
authors.forename: C A
authors.initials: CA
authors.lastname: Angell