2022.02.04
Research teams led by Professor Kwan-Pyo Kim (Department of Physics, Yonsei University) and Professor Chae-woon Kim, Ulsan Institute of Science and Technology, have observed the liquid phase transition process of fullerene molecular crystals at a single molecular level.
Phase transition is the phenomenon in which a material changes from one phase to another according to certain external conditions such as temperature, pressure, and external magnetic field. For example, the condensation phenomenon in which the gas transitions to the liquid and the coagulation phenomenon in which the liquid transitions to the solid is a representative phase transition phenomenon that can be seen in everyday life.
The phenomenon of phase transition has been studied indirectly through model experiments and computer simulations. This is because there are several experimental constraints to observe phase transitions accurately at a single atomic or molecular level. In particular, in the liquid state, the molecular arrangement is irregular and each molecule is actively moving, it is difficult to measure the location information of a single molecule in real time.
The researchers solved this difficulty by producing fullerene molecular crystals on graphene. Fullerene is one of the carbon allotropes, in which carbon atoms combine in a pentagonal or hexagonal shape to form a spherical molecule. Fullerene has the advantage of high stability to the electron beam and easy to observe with an electron microscope. Graphene supported fullerene molecules in the liquid state and served to minimize noise that could be a problem during electron microscopy observation.
"In the past, we have indirectly studied the phenomenon of phase transition by model experiments and computer simulations, but this time we have directly observed the phenomenon of phase transition by real molecular crystals into liquids," said Professor Kwan-pyo Kim.
The results of this study were published on the 27th of the International journal Nature Communications.