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Updated: Jun 21, 2026

Cooling Rate Dependent Ellipsometry Measurements to Determine the Dynamics of Thin Glassy Films
Published on: January 26, 2016
Evidence of a two-state picture for supercooled water and its connections with glassy dynamics
G A Appignanesi1, J A Rodriguez Fris, F Sciortino
1Area de Fisicoquímica, Departamento de Química and INQUISUR, Universidad Nacional del Sur, 8000 Bahía Blanca, Argentina.
Abstract:
The picture of liquid water as consisting of a mixture of molecules of two different structural states (structured, low-density molecules and unstructured, high-density ones) represents a belief that has been around for long time awaiting for a conclusive validation. While in the last years some indicators have indeed provided certain evidence for the existence of structurally different "species", a more definite bimodality in the distribution function of a sound structural quantity would be desired. In this context, our present work combines the use of a structural parameter with a minimization technique to yield neat bimodal distributions in a temperature range within the supercooled liquid regime, thus clearly revealing the presence of two populations of differently structured water molecules. Furthermore, we elucidate the role of the inter-conversion between the identified two kinds of states for the dynamics of structural relaxation, thus linking structural information to dynamics, a long-standing issue in glassy physics.
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