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Máximas en las funciones de respuesta termodinámica y correlación de agua superenfriada

Kyung Hwan Kim¹, Alexander Späh¹, Harshad Pathak¹

¹Department of Physics, AlbaNova University Center, Stockholm University, SE-10691 Stockholm, Sweden.

Science (New York, N.Y.)

|December 23, 2017

Resumen

Los investigadores utilizaron pulsos láser de rayos X para estudiar las gotas de agua superenfriadas. Los hallazgos sugieren que existe una línea de Widom en agua profundamente superenfriada, influenciada por efectos cuánticos nucleares.

Área de la Ciencia:

Química Física
La termodinámica
Física de la materia blanda

Sus antecedentes:

El agua exhibe un comportamiento complejo en su estado súper enfriado, con anomalías que sugieren un punto crítico líquido-líquido.
Comprender la termodinámica del agua súper enfriada es crucial para varios campos científicos.

Objetivo del estudio:

Probar experimentalmente la respuesta termodinámica y las funciones de correlación del agua sobreenfriada y del agua pesada.
Identificar la presencia y las características de una línea de Widom en agua superenfriada.

Principales métodos:

Utilizó pulsos láser de rayos X de femtosegundos para investigar gotas de agua de tamaño micrométrico enfriadas a 227 Kelvin en el vacío.
Se analizaron datos de dispersión de rayos X en la región de transferencia de bajo momento para extraer la compresibilidad isotérmica y la longitud de correlación.

Principales resultados:

Máximos observados en la respuesta termodinámica y las funciones de correlación a 229 K para el agua y 233 K para el agua pesada.
Detectó el crecimiento más rápido de estructuras tetraédricas en ambos isótopos de agua alrededor de estas temperaturas.
La diferencia isotópica en la compresibilidad isotérmica destaca la importancia de los efectos cuánticos nucleares.

Conclusiones:

Los resultados experimentales proporcionan evidencia de la existencia de una línea de Widom en el régimen de agua profundamente superenfriada.
Estos hallazgos contribuyen a comprender las propiedades anómalas del agua y el papel de los efectos cuánticos en su comportamiento de fase.

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