Electric charging effects on insulating surfaces in cryogenic liquids
Wolfgang Korsch1, Mark Broering1,2, Ashok Timsina1
1Department of Physics and Astronomy, University of Kentucky, Lexington, Kentucky 40506, USA.
The Review of Scientific Instruments
|April 1, 2024
Summary
This study introduces a novel cryoliquid technique to observe ion adsorption on insulating surfaces. Results show similar ion behavior on different surfaces, impacting cryogenic experiments like the neutron electric dipole moment search.
Area of Science:
- Surface science
- Cryogenics
- Materials science
Background:
- Studying ion and electron interactions with insulating surfaces in cryoliquids is crucial for understanding fundamental processes.
- Strong electric fields in cryogenic environments present unique challenges for surface interaction studies.
Purpose of the Study:
- To develop and demonstrate a new experimental technique for investigating ion adsorption/desorption on insulating surfaces in cryoliquids under strong electric fields.
- To compare the behavior of ions on pristine poly(methyl methacrylate) (PMMA) versus a modified PMMA surface.
- To measure the dielectric constant of PMMA at cryogenic temperatures.
Main Methods:
- Utilized a compact cryostat integrated with an electro-optical Kerr device for precise electric field monitoring.
- Investigated nitrogen and helium ion interactions with PMMA and a PMMA/deuterated polymer mixture.
- Employed the setup to determine the quasi-static dielectric constant of PMMA at approximately 70 K.
Main Results:
- Successfully observed and quantified ion accumulation and removal on both tested surfaces.
- Demonstrated similar adsorption/desorption behavior for physisorbed ions on both pristine and modified PMMA surfaces within experimental precision.
- Obtained the dielectric constant of PMMA at ~70 K.
Conclusions:
- The developed technique effectively studies ion-surface interactions in cryogenic liquids.
- The similar behavior of physisorbed ions suggests robustness of the observed phenomena across different surface chemistries.
- Findings are relevant for optimizing cryogenic experiments, including the search for a neutron permanent electric dipole moment (nEDM).
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