"Warm ice and homogeneous melting of an ice crystal: a not so short story"

Datum

18.06.2019

Zeit

17:00 - 18:30

Sprecher

Prof. Roberto Bini: Università degli Studi di Firenze

Sprache

en

Hauptthema

Materialien

Andere Themen

Materialien

Host

Prof. Felser, Prof. Grin, Prof. Ruck, Prof. Kaskel, Prof. Weigand

Beschreibung

Homogeneous melting of crystals is a complex multistep process involving the formation of transient states at temperatures considerably higher than the melting point. The nature and persistence of these metastable structures are intimately connected to the melting process and a precise definition of the temporal boundaries of these phenomena is not yet available. We set up specifically designed experiments to probe by Mie scattering and transient infrared absorption spectroscopy the entire dynamics, ranging from tens of picoseconds to milliseconds, of superheating, melting and recrystallization of an ice crystal. In spite of a large excess of energy provided, only about 30% of the micrometric crystal liquefies in the first 20-25 ns because of the incredibly long persistence of the superheated metastable phase that extends for more than 100 ns. This behavior is ascribed to the population of low energy states that trap a large amount of energy favoring the formation of a metastable plastic ice phase.

Links

• MPI CPfS

Letztmalig verändert: 19.06.2019, 00:10:35