Design and characterization of a tunable open TE₀₁₁ resonator for Q-band pulse EPR experiments

Area of Science:

• Biophysics
• Spectroscopy
• Materials Science

Background:

• Electron Paramagnetic Resonance (EPR) is crucial for studying metalloproteins and enzymes.
• Versatile instrumentation is needed to address diverse research questions in this field.

Purpose of the Study:

• To explore the utility of an open resonator concept for a general-use, highly tunable TE011 resonator at Q-band frequencies (≈ 34 GHz).
• To design and experimentally characterize a resonator prioritizing ease of execution, handling, and affordability.

Main Methods:

• Proof-of-concept calculations to establish critical parameter ranges.
• Design and construction of a TE011 open resonator.
• Experimental characterization of tunability, coupling, and frequency adjustment using movable plungers.

Main Results:

• The resonator demonstrated high tunability, allowing critical and overcoupled states with a three-fold bandwidth change.
• Frequency tuning via axial plungers enables compatibility with narrow-bandwidth microwave instrumentation and diverse samples.
• The design's tolerance for manufacturing imperfections makes it affordable and easy to build.

Conclusions:

• The developed Q-band TE011 open resonator offers significant tunability and versatility for EPR spectroscopy.
• Its robust and affordable design facilitates broader application in metalloprotein and enzyme research.
• The resonator's adaptability enhances its long-term utility in various research settings.