State of water at 136 K determined by its relaxation time.

Dielectric relaxation time of pure bulk water has been determined from the dielectric loss tangent scans against temperature at two frequencies. After calculating the frequency-independent background loss, the relaxation loss was obtained, and the relaxation time determined. The dielectric relaxation time of water is 35 +/- 13 s at 136 +/- 1 K, which is comparable with its structural relaxation time of ca. 33 s estimated from its T(g) endotherm (G. P. Johari, A. Hallbrucker and E. Mayer, Nature, 1987, 330, 552). Therefore, water is an ultraviscous liquid at 136 K, and this removes the basis for a comparison-based inference that water is a rigid glass up to a temperature of 165 K or higher (Y. Yue and C. A. Angell, Nature, 2004, 427, 717). The method yields satisfactory values for the relaxation time of stable glasses at their known calorimetric T(g).