2020 Fiscal Year Annual Research Report
Electronic structure characterization of non-aqueous solvents
| Project/Area Number |
18K14178
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| Research Institution | Kyoto University |
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Principal Investigator |
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| Project Period (FY) |
2018-04-01 – 2021-03-31
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| Keywords | electron spectroscopy / non-aqueous solvents / electronic structure / ionization energy / valence band |
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| Outline of Annual Research Achievements |
This project's aim was to study the electronic structure of liquids, with focus on non-aqueous solutions, in novel ways using photoelectron spectroscopy.
For the first time, the full valence band of ethanol and methanol was successfully characterized, which revealed that, unlike water, the molecular character is largely preserved even in the liquid state for these alcohols. The measurement protocol established here will be expanded to acetonitrile, propanol and other chemically relevant liquids in the future.
In parallel, a novel energy-referencing method for measuring absolute ionization energies was developed and applied to liquid water. Measuring accurate ionization energies is a prerequisite to study the electronic structure and chemistry of solutions. Applying this method to above alcohols revealed a distinct energy shift in ethanol, which hints at the presence of surface dipoles from orientated molecules at the liquid's surface. This may pave the way for novel ways to study the surface structure of liquids.
Furthermore, measurements of liquid ammonia with a unprecedented cryogenic liquid-jet have been made possible in international collaboration, which enabled first direct study of a insulator-to-metal transition in an alkali metal-ammonia solution. The gained knowledge was applied to study metallic water-solutions by forming a liquid water layer on a sodium-potassium droplet.
Overall, the project has expanded the scope and applicability of photoelectron spectroscopy to both aqueous and non-aqueous solutions for studying novel phenomena and chemically relevant parameters.
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