Cold Melting

Cold Melting

Author: ChemistryViews

Inverse melting – the transition from a crystalline to a less ordered phase upon cooling – is rare but has been shown to occur, typically in systems under extreme pressures.

A. Schöll, Universität Würzburg, Germany, and co-workers have demonstrated that inverse melting can occur in 2 D systems using a monolayer of 1,4,5,8-naphthalene-tetracarboxylic dianhydride on a silver surface without application of external pressure.

They show that the high-resolution low-energy electron diffraction (LEED) pattern disappears upon cooling to 155 K and reappears at around 190 K. The loss of the diffraction spots represents the loss of long-range order within the system and the formation of a low-temperature monolayer phase. They show the phase transition is reversible and can be repeated numerous times, being driven by strongly anisotropic interactions between the monolayer and the metal surface.

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