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Observación experimental de la transición líquido-líquido en agua sobreenfriada a granel bajo presión
Kyung Hwan Kim1,2, Katrin Amann-Winkel1, Nicolas Giovambattista3,4
1Department of Physics, AlbaNova University Center, Stockholm University, SE-10691 Stockholm, Sweden.
Science (New York, N.Y.)
|November 20, 2020
Resumen
Los investigadores observaron una transición de líquido a líquido en agua súper enfriada bajo presión. El calentamiento ultrarrápido del hielo amorfo reveló distintos dominios de baja densidad que se forman antes de la cristalización, apoyando esta transición de fase.
Área de la Ciencia:
- Química Física
- Física de la materia condensada
- Ciencias de los materiales
Sus antecedentes:
- El agua súper enfriada exhibe un comportamiento complejo bajo condiciones de presión y temperatura variables.
- Comprender las transiciones de fase del agua es crucial para varias disciplinas científicas.
Objetivo del estudio:
- Investigar la dinámica estructural del agua sobreenfriada a granel bajo presión.
- Para proporcionar pruebas de una transición de fase líquido-líquido en el agua.
Principales métodos:
- Calentamiento isocórrico de hielo amorfo de alta densidad utilizando un láser de femtosegundos.
- Análisis estructural ultrarrápido a través de pulsos de rayos X de femtosegundos.
- Monitoreo de la descompresión y los cambios estructurales en escalas de tiempo de nanosegundos a microsegundos.
Principales resultados:
- Se preparó agua líquida de alta densidad a 205 K y 2.5-3.5 kbar.
- Se observó un cambio estructural discontinuo, con la aparición y el crecimiento de dominios líquidos de baja densidad.
- La cristalización ocurrió en escalas de tiempo más largas (3-50 microsegundos), separadas de la formación del dominio.
Conclusiones:
- La separación observada en escalas de tiempo apoya una transición líquido-líquido en agua súper enfriada.
- La difracción de rayos X en femtosegundos es una herramienta poderosa para estudiar las transiciones de fase ultrarrápidas en el agua.
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