Abnormal phase transition between two-dimensional high-density liquid crystal and low-density crystalline solid phases

Authors

Wenbin Li, University of Chinese Academy of Sciences
Longjuan Kong, University of Chinese Academy of Sciences
Baojie Feng, Chinese Academy of Sciences
Huixia Fu, University of Chinese Academy of Sciences
Hui Li, Beijing University of Chemical TechnologyFollow
Xiao Cheng Zeng, University of Nebraska-LincolnFollow
Kehui Wu, Chinese Academy of SciencesFollow
Lan Chen, Chinese Academy of SciencesFollow

ORCID IDs

Baojie Feng http://orcid.org/0000-0003-2332-7949

Xiao Cheng Zeng http://orcid.org/0000-0003-4672-8585

Date of this Version

2018

Citation

NATURE COMMUNICATIONS (2018) 9:198

DOI: 10.1038/s41467-017-02634-6

Comments

Open Access This article is licensed under a Creative Commons Attribution 4.0 International License

Abstract

Some two-dimensional liquid systems are theoretically predicted to have an anomalous phase transition due to unique intermolecular interactions, for example the first-order transition between two-dimensional high-density water and low-density amorphous ice. However, it has never been experimentally observed, to the best of our knowledge. Here we report an entropy-driven phase transition between a high-density liquid crystal and low-density crystalline solid, directly observed by scanning tunneling microscope in carbon monoxide adsorbed on Cu(111). Combined with first principle calculations, we find that repulsive dipole–dipole interactions between carbon monoxide molecules lead to unconventional thermodynamics. This finding of unconventional thermodynamics in two-dimensional carbon monoxide not only provides a platform to study the fundamental principles of anomalous phase transitions in two-dimensional liquids at the atomic scale, but may also help to design and develop more efficient copper-based catalysis.