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Crecimiento y estructura de las primeras capas de hielo en Ru(0001) y Pt(111)
Sabine Maier1,2, Barbara A J Lechner1, Gabor A Somorjai1,3
1Materials Sciences Division, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States.
Journal of the American Chemical Society
|February 5, 2016
Resumen
Investigar el agua en las superficies metálicas revela que la capa de agua inicial
Área de la Ciencia:
- Ciencias de la superficie
- Física de la materia condensada
- Física y química
Sus antecedentes:
- La adsorción de agua en las superficies metálicas es crucial para comprender varios fenómenos.
- Las capas iniciales de agua dictan la estructura de la posterior formación de hielo.
- Ru(0001) y Pt(111) son sistemas modelo para el estudio de las interacciones superficiales.
Objetivo del estudio:
- Para aclarar la estructura a nivel molecular y el crecimiento de las capas iniciales de agua en Ru{0001) y P{111).
- Para investigar la transición de las estructuras de hielo amorfo a cristalino.
- Para identificar los defectos estructurales que influyen en la formación de hielo.
Principales métodos:
- Se empleó microscopía de túnel de barrido (STM) para lograr una resolución a nivel molecular.
- Los experimentos se llevaron a cabo en superficies metálicas de Ru (0001) y Pt (111).
- Se utilizaron temperaturas variables para observar diferentes fases de hielo.
Principales resultados:
- La primera capa de agua forma estructuras hexagonales, tanto ordenadas como desordenadas con el sustrato.
- Estos hexágonos se conectan a través de unidades pentagonales y heptagonales, lo que lleva al crecimiento de hielo amorfo en capas más altas por debajo de 140 K.
- Tras la transición al hielo cristalino, la capa inicial se reconfigura para que coincida con la simetría hexagonal del sustrato.
- Se identificaron defectos estructurales, incluidos anillos de cinco y ocho miembros, como límites de dominio y fallas de apilamiento.
- Estos defectos contribuyen a la formación de hielo cúbico metastable.
Conclusiones:
- La estructura de la primera capa de agua influye críticamente en el crecimiento y la fase subsiguientes del hielo.
- Las estructuras de hielo amorfo y cúbico metastables se forman debido a disposiciones y defectos interfaciales específicos.
- Comprender estas estructuras interfaciales del agua es clave para controlar los procesos de formación de hielo.
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