10:45 〜 12:15
[MIS14-P04] ペルチェ式冷却TEM ホルダーと溶液セルを用いた氷結晶その場観察
キーワード：その場観察、氷、透過型電子顕微鏡、溶液セル、結晶化
In situ observation of crystallization from solution or melt is an important technique for understanding the mechanisms of nucleation and crystal growth. Phenomena occurring at the nanoscale, such as nucleation, are difficult to observe in situ because they require high spatial and temporal resolution. One technique that makes this possible may be liquid-cell transmission electron microscopy (LC-TEM), in which a volatile sample is encapsulated between two thin films (amorphous silicon nitride or graphene) and introduced into the vacuum environment of the TEM in an isolated state. This method has been used to capture crystallization processes from solution [1,2], but it is still difficult to capture nucleation efficiently because there are few effective ways to control supersaturation in the liquid cell. To solve this problem, we have attempted to control the supersaturation by using electron beam radiolysis [3] and dielectrophoresis with electrodes [4]. To change the supersaturation more easily in a wide range of systems, we have developed a TEM holder equipped with Peltier elements, which can control the temperature to minus several tens of degrees Celsius. To test the system, which combines the Peltier cooling TEM holder and a liquid cell, we attempted water crystallization experiments.
A liquid cell with amorphous silicon nitride thin films was filled with pure water as the sample and mounted on the tip of the Peltier cooling TEM holder. The temperature at the sample position was cooled from room temperature to about -20 °C, and the sample was observed in situ by TEM.
Bubbles were generated from the sample when the sample was cooled. These bubbles remained at the position where they were generated and did not move. This was due to the formation of gas in the solid, suggesting that the water turned into ice. The bubbles disappeared when the ice crystals were dissolved by increasing the temperature. Electron diffraction patterns of the generated ice crystals were obtained and analyzed, and it was found that the crystals were ice Ih. We will report and discuss the results of in situ observations of ice crystals made with this observation technique.
Acknowledgements
This work was supported by JSPS KAKENHI Grant Numbers 20H02580 and 20H05657.
[1] M. H. Nielsen et al., Science 345 (2014) 1158.
[2] T. Yamazaki et al., Proc. Natl. Acad. Sci. USA 114 (2017) 2154.
[3] T. Yamazaki & Y. Kimura, Microsc. Microanal. 27 (2021) 459.
[4] T. Yamazaki et al., Microscopy 71 (2022) 231.
A liquid cell with amorphous silicon nitride thin films was filled with pure water as the sample and mounted on the tip of the Peltier cooling TEM holder. The temperature at the sample position was cooled from room temperature to about -20 °C, and the sample was observed in situ by TEM.
Bubbles were generated from the sample when the sample was cooled. These bubbles remained at the position where they were generated and did not move. This was due to the formation of gas in the solid, suggesting that the water turned into ice. The bubbles disappeared when the ice crystals were dissolved by increasing the temperature. Electron diffraction patterns of the generated ice crystals were obtained and analyzed, and it was found that the crystals were ice Ih. We will report and discuss the results of in situ observations of ice crystals made with this observation technique.
Acknowledgements
This work was supported by JSPS KAKENHI Grant Numbers 20H02580 and 20H05657.
[1] M. H. Nielsen et al., Science 345 (2014) 1158.
[2] T. Yamazaki et al., Proc. Natl. Acad. Sci. USA 114 (2017) 2154.
[3] T. Yamazaki & Y. Kimura, Microsc. Microanal. 27 (2021) 459.
[4] T. Yamazaki et al., Microscopy 71 (2022) 231.