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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 9: Crystallization, Nucleation and Self-Assembly II

CPP 9.8: Talk

Monday, March 18, 2024, 17:00–17:15, H 2032

Atomic imaging of the critical nucleus size of multilayer hexagonal ice growth — •Dong Guan, Tiancheng Liang, Zixiang Yan, Li-Mei Xu, En-Ge Wang, and Ying Jiang — International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China

Multilayer water ice growth is widespread and plays a significant role in various natural phenomena. An essential aspect of water ice growth is the elusive nature of the critical ice nucleus, attributed to its transient and delicate characteristics. We present the precise atomic size of the critical ice nucleus in hexagonal water ice (ice Ih) through the utilization of qPlus-based cryogenic noncontact atomic force microscopy (NC-AFM) equipped with a CO-terminated tip. Freezing samples during the growth process allows us to capture the intermediate structures involved in the growth of Ih ice. Our investigation reveals that pentamers and hexamers are the most prevalent intermediate structures, and their combination gives rise to the 3-5 cluster, which we define as the critical ice nucleus. Combined with density functional theory, we might show that the structure alteration of the 3-5 cluster results in the formation of a new core for Ih ice. This new core can expand by incorporating additional water molecules along its periphery. This research is the first achievement in elucidating the exact atomic structure of a critical ice nucleus in water. It provides valuable insights into the water freezing process and holds the potential for application to other nucleation processes.

Keywords: Hexagonal water ice; Critical nucleus; NC-AFM