Dynamic Crossover in Deeply Cooled Water Confined in MCM-41 at 4 Kbar and its Relation to the Liquid-Liquid Transition Hypothesis

Published

September 11, 2015

Author(s)

Zhe Wang, Peisi Le, Kanae Ito, Juscelino Leao, Madhu Sudan Tyagi, Sow-Hsin Chen

Abstract

With quasi-elastic neutron scattering (QENS), we study the single-particle dynamics of the water confined in a hydrophilic silica material, MCM-41, at 4 kbar. A dynamic crossover phenomenon is observed at 219 K. We compare this dynamic crossover with the one observed at ambient pressure, and find that: (a) above the crossover temperature, the temperature dependence of the characteristic relaxation time at ambient pressure exhibits a more evident super-Arrhenius behavior than that at 4 kbar. (b) Below the crossover temperature, the Arrhenius behavior found at ambient pressure has a larger activation energy compared to the one found at 4 kbar. We ascribe the former to the difference between the local structure of the low-density liquid (LDL) phase and that of the high-density liquid (HDL) phase, and the latter to the difference between the strength of the hydrogen bond of the LDL and that of the HDL. Therefore, we conclude that the phenomena observed in this paper are consistent with the LDL-to-HDL liquid-liquid transition hypothesis.

Citation

Journal of Chemical Physics

Volume

143

Issue

11

Pub Type

Journals

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Keywords

water, dynamics, neutron scattering

Citation

Wang, Z. , Le, P. , Ito, K. , Leao, J. , Tyagi, M. and Chen, S. (2015), Dynamic Crossover in Deeply Cooled Water Confined in MCM-41 at 4 Kbar and its Relation to the Liquid-Liquid Transition Hypothesis, Journal of Chemical Physics, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=919065 (Accessed April 16, 2024)