2022 Fiscal Year Research-status Report
Electron Scattering and Electron Angular Anisotropy in Water and Aqueous Solution
| Project/Area Number |
20K15229
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| Research Institution | Kyoto University |
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Principal Investigator |
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| Project Period (FY) |
2020-04-01 – 2024-03-31
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| Keywords | electron spectroscopy / electron scattering / liquid water / photoelectron anisotropy |
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| Outline of Annual Research Achievements |
The project gives new insights into electron scattering mechanisms in liquid water and aqueous solutions and its impact on photoelectron angular distributions using photoelectron spectroscopy in international collaboration. Electron scattering is crucial for understanding energy deposition, radical formation, and biological damage by slow and fast electrons, and a correct interpretation of spectra from liquid water and aqueous solutions.
In the past year, it was demonstrated that surface-active molecules (here: perfluoropentanoate) in aqueous solution can be precisely mapped using photoelectron angular distributions (PADs). Electron scattering alters the PAD signature in a way that is uniquely linked to the probing depth down to an Angstrom resolution. Combined with the chemical specificity of photoemission, this novel technique paves the way to study the detailed surface composition of solutions relevant for, e.g., atmospheric chemistry.
Recent results reveal that electron scattering affects surface-active species differently than bulk species. Photoelectrons from the surface do not suffer from scattering in the bulk liquid, and are thus detectable down to much lower kinetic energies. This distinction is crucial to understand photoelectron spectra from low-energy sources such as lasers, which might be misinterpreted if the surface-propensity and concentration is not considered. These results are currently prepared for publication.
Furthermore, a method for accessing the work function (surface potential) of aqueous solutions has been developed and is currently under review.
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| Current Status of Research Progress |
Current Status of Research Progress
1: Research has progressed more than it was originally planned.
Reason
The project has already revealed many new insights into electron scattering, such as a largely enhanced scattering behavior in bulk liquid water at low kinetic energies, which is however not observed at the interface. Furthermore, a novel energy-referencing scheme was developed which will become the new standard in photoemission from liquids. Now in its final stage, the project concentrates more on the behavior of solutes, both in terms of electron scattering and angular anisotropy. Thanks to the end of the pandemic, on-site experiments in Europe are possible again, which is ideal to wrap up the project.
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| Strategy for Future Research Activity |
The final stage of the project will further explore electron scattering in the low kinetic-energy regime in liquid water and aqueous solution. Here, also the role of the solute (bulk and surface-active ones) will become a larger focus. This will culminate in a modernized description of the photoelectron spectra of liquid water and aqueous solution alike with the proper inclusion of all relevant scattering processes.
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| Causes of Carryover |
Expenses are used as follows: International travel has become possible again, and travel to experiments in Europe are planned for autumn and / or spring of the following year. Also, inviting a researcher to Japan for close collaboration is planned. Both will help greatly to achieve the proposed goals.
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[Presentation] Photoelectron Circular Dichroism from Aqueous-Phase Biomolecules2023
Author(s)
M. Pugini, D. Stemer, K. Mudryk, L. Tomanik, S. Malerz, F. Trinter, T. Buttersack, U. Hergenhahn, I. Wilkinson, S. Thuermer, P. Slavicek, B. Winter, G. Meijer
Organizer
DESY Photon Science Users' Meeting 2023
Int'l Joint Research
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[Presentation] Photoemission Studies On A Liquid Jet At The Petra III Beamline P042022
Author(s)
F. Trinter, S.Malerz, K. Mudryk, D. Stemer, M. Pugini, T. Buttersack, M.N. Pohl, I. Wilkinson, U. Hergenhahn, S. Thuermer, B. Winter
Organizer
SNI2022
Int'l Joint Research
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[Presentation] Photoemission from aqueous solutions at PETRA III beamline P04: Towards detecting Photoelectron Circular Dichroism (PECD)2022
Author(s)
S. Malerz, F. Trinter, U. Hergenhahn, T. Buttersack, D. Stemer, K. Mudryk, M. Pohl, G. Meijer, I. Wilkinson, S. Thuermer, B. Winter
Organizer
14th International Conference on Synchrotron Radiation Instrumentation (SRI) 2022
Int'l Joint Research
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