Axially uniform magnetic field-modulation excitation for electron paramagnetic resonance in rectangular and cylindrical cavities by slot cutting

Sidabras, Jason W.; Richie, J.E.; Hyde, James S.

doi:10.1016/j.jmr.2016.11.014

Cited by 3 publications

(2 citation statements)

References 17 publications

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“…Design of the field modulation slots is produced by the following: i) simulating the 100 kHz field modulation profile in the region-of-interest for n slots of equal depth, ii) reducing the central slots by approximately half, and iii) adjusting slots to minimize ripple along the sample [9]. After each step a simulation is run and uniformity along the axis of the sample is calculated.…”

Section: Designmentioning

confidence: 99%

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Uniform field loop-gap resonator and rectangular TE U02 for aqueous sample EPR at 94 GHz

Sidabras

Sarna

Mett

et al. 2017

Journal of Magnetic Resonance

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In this work we present the design and implementation of two uniform-field resonators: a seven-loop–six-gap loop-gap resonator (LGR) and a rectangular TEU02 cavity resonator. Each resonator has uniform-field-producing end-sections. These resonators have been designed for electron paramagnetic resonance (EPR) of aqueous samples at 94 GHz. The LGR geometry employs low-loss Rexolite end-sections to improve the field homogeneity over a 3 mm sample region-of-interest from near-cosine distribution to 90% uniform. The LGR was designed to accommodate large degassable Polytetrafluorethylen (PTFE) tubes (0.81 mm O.D.; 0.25 mm I.D.) for aqueous samples. Additionally, field modulation slots are designed for uniform 100 kHz field modulation incident at the sample. Experiments using a point sample of lithium phthalocyanine (LiPC) were performed to measure both the uniformity of the microwave magnetic field and 100 kHz field modulation, and confirm simulations. The rectangular TEU02 cavity resonator employs over-sized end-sections with sample shielding to provide an 87% uniform field for a 0.1 × 2 × 6 mm3 sample geometry. An evanescent slotted window was designed for light access to irradiate 90% of the sample volume. A novel dual-slot iris was used to minimize microwave magnetic field perturbations and maintain cross-sectional uniformity. Practical EPR experiments using the application of light irradiated rose bengal (4,5,6,7-tetrachloro-2′,4′,5′,7′-tetraiodofluorescein) were performed in the TEU02 cavity. The implementation of these geometries providing a practical designs for uniform field resonators that continue resonator advancements towards quantitative EPR spectroscopy.

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Section: Designmentioning

confidence: 99%

“…introduced methodology to produce uniform 100 kHz field modulation incident on the sample by numerically optimizing the modulation slot depth [9]. In the present work, this methodology was used to optimize, simulate, and implement uniform 100 kHz field modulation slot design in the seven-loop–six-gap LGR geometry.…”

Section: Introductionmentioning

confidence: 99%

Uniform field loop-gap resonator and rectangular TE U02 for aqueous sample EPR at 94 GHz

Sidabras

Sarna

Mett

et al. 2017

Journal of Magnetic Resonance

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Autobiography of James S. Hyde

Hyde

2017

Appl Magn Reson

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The papers, book chapters, reviews, and patents by James S. Hyde in the bibliography of this document have been separated into EPR and MRI sections, and within each section by topics. Within each topic, publications are listed chronologically. A brief summary is provided for each patent listed. A few publications and patents that do not fit this schema have been omitted. This list of publications is preceded by a scientific autobiography that focuses on selected topics that are judged to have been of most scientific importance. References to many of the publications and patents in the bibliography are made in the autobiography.

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Design and performance of an oversized-sample 35 GHz EPR resonator with an elevated Q value

Fischer,

Stropp,

Tschaggelar

et al. 2024

Magn. Reson.

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Abstract. Continuous-wave electron paramagnetic resonance (EPR) spectroscopy at 35 GHz is an essential cornerstone in multi-frequency EPR studies and is crucial for differentiating multiple species in complex systems due to the improved g-tensor resolution compared to lower microwave frequencies. Especially for unstable and highly sensitive paramagnetic centers, the reliability of the measurements can be improved upon through the use of a single sample for EPR experiments at all frequencies. Besides the advantages, the lack of common availability of oversized-sample resonators at 35 GHz often limits scientists to lower frequencies or smaller sample geometries, and the latter may be non-trivial for sensitive materials. In this work, we present the design and performance of an oversized-sample 35 GHz EPR resonator with a high loaded Q value, QL, of up to 2550, well-suited for continuous-wave EPR and pulsed single-microwave-frequency experiments. The design is driven by electromagnetic field simulations, and the microwave characteristics of manufactured prototypes were found to be in agreement with the predictions. The resonator is based on a cylindrical cavity with a TE011 mode, allowing for 3 mm sample access. The design targets that we met include high sensitivity, robustness, and ease of manufacturing and maintenance. The resonator is compatible with commercial EPR spectrometers and with helium flow, as well as with cryogen-free cryostats, allowing for measurements at temperatures down to 1.8 K. To highlight the general applicability, the resonator was tested on metal centers, as well as on organic radicals featuring extremely narrow lines.

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Axially uniform magnetic field-modulation excitation for electron paramagnetic resonance in rectangular and cylindrical cavities by slot cutting

Cited by 3 publications

References 17 publications

Uniform field loop-gap resonator and rectangular TE U02 for aqueous sample EPR at 94 GHz

Uniform field loop-gap resonator and rectangular TE U02 for aqueous sample EPR at 94 GHz

Autobiography of James S. Hyde

Design and performance of an oversized-sample 35 GHz EPR resonator with an elevated Q value

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