2020 Fiscal Year Annual Research Report
液中TEM技術によるナノスケール沸騰現象の直接観測
| Project/Area Number |
20J13061
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| Research Institution | Kyushu University |
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Principal Investigator |
NAG SARTHAK 九州大学, 工学府, 特別研究員(DC2)
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| Project Period (FY) |
2020-04-24 – 2022-03-31
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| Keywords | surface nanobubbles / electron microscopy / phase change / in-situ observation |
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| Outline of Annual Research Achievements |
In the previous fiscal year, we used the liquid phase electron microscopy (LPEM) technique to study the surface nanobubbles in a thin liquid film. Our focus was on studying the longevity of the surface nanobubbles; hence we designed our experiments to observe nanobubble coalescence. It was found that the surface nanobubbles are hesitant towards merging phenomenon, and gas transfer mostly occurs via Ostwald Ripening. However, for the equally sized bubbles in vicinity, the localized saturation plays an important role in merging. Specifically, a thin gas layer is formed between the bubbles which acts as a bridge and initiate the bubble merging. The research results were disseminated in form of a journal paper (Langmuir) and three conferences.
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
The initial plan to use graphene was changed due to the problems like large transfer and sample contaminations at nanoscale level while liquid cell fabrication, which hindered imaging and bubble nucleation. However, the in-situ study of nanobubbles using the liquid phase electron microscopy was performed efficiently on the hydrophilic surface. Moreover, the collaborations have helped to perform experiments flexibly by making enough equipment time available for the experiments. In house image analysis code was developed which helped in efficient analysis of our results.
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| Strategy for Future Research Activity |
For the FY2021, nanobubbles will be further investigated using advanced TEM techniques. Last year, while studying coalescence, repulsions between the nanobubble interfaces and their unique behaviour was observed. These findings have potential to settle the debate on the unexplained longevity of the nanobubbles. Hence, to understand the physics behind these observations, we plan to utilise the advanced spectroscopy techniques in TEM. Additionally, the research results will be disseminated in numerous conferences.
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