Analysis of two stacked cylindrical dielectric resonators in a TE102 microwave cavity for magnetic resonance spectroscopy

Mattar, Saba M.; Elnaggar, Sameh Y.

doi:10.1016/j.jmr.2011.01.004

Cited by 16 publications

(14 citation statements)

References 55 publications

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“…21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 …”

Section: Discussionunclassified

Single Crystal Electron Paramagnetic Resonance with Dielectric Resonators of Mononuclear Cu²⁺ Ions in a Metal–Organic Framework Containing Cu₂ Paddle Wheel Units

et al. 2015

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Dielectric resonator aided sensitivity-enhancing electron paramagnetic resonance was successfully applied to small single crystals of the previously reported metal-organicin a conventional X-band EPR spectrometer at 7 K sample temperature to reveal the nature of mononuclear Cu 2+ ion defect species. We found that these paramagnetic defects are not related to an impurity phase or extraframework species of the parent metal-organic framework material but are formed within the framework. Novel angular resolved single crystal continuous wave electron paramagnetic resonance supported by powder measurements and single crystal X-ray diffraction on this metal-organic framework compound identified defective copper paddle wheel units with one missing Cu 2+ ion as the observed mononuclear paramagnetic species in this compound. The sensitivity enhancement by an estimated factor of 8.6 for the single crystal electron paramagnetic resonance spectroscopy is required to efficiently record the Cu 2+ ion signals in single crystals of typical sizes of 200 × 50 × 50 µm 3 at X-band frequencies. The results demonstrate that conventional electron paramagnetic resonance spectrometers operating at X-band frequencies and equipped with dielectric resonators can successfully be used to perform single crystal studies of these porous, low density materials with very small volume samples at low temperatures.

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Section: Discussionunclassified

Single Crystal Electron Paramagnetic Resonance with Dielectric Resonators of Mononuclear Cu²⁺ Ions in a Metal–Organic Framework Containing Cu₂ Paddle Wheel Units

et al. 2015

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“…Those with higher e r and comparable geometry enhance the field a little bit more, while a hole enhances the field significantly more because of the more suitable position of the sample. Theory for the latter observations is covered by other authors already [7]. Special care has to be taken to position the sample right in the middle of the disk.…”

Section: B 1 -Field Conversionmentioning

confidence: 99%

“…Different shapes and designs for DRs have been proposed. They are treated to great extend in [4][5][6][7][8] and are nowadays available in industry design such as the Bruker ER 4123D and 4118X-MD5 resonators. Some DRs were coupled via antennae [9] while others have integrated them into cavity resonators, such as Mattar and Emwas [10] who report signal-to-noise ratio (SNR) gains of stacked DRs of 24 and Jaworski et al [1] with SNR gains of more than 30 at room temperature depending on the sample.…”

Section: Introductionmentioning

confidence: 99%

“…Here, a thin capillary (ø = 200 lm) is positioned with grease inside the hole of K80 (ø = 1 mm). c Superposition of TE 01d -mode of a DR (thin, red) and TE 102 mode of the cavity resonator (dashed, blue) in the notation of [16] (color online) simulations and CMT of DRs coupled to cavity resonators found the TE 01d mode being able to couple in a parallel (symmetric, in phase) and antiparallel (antisymmetric, out of phase) configuration with respect to the TE 102 or TM 110 modes of the rectangular or cylindrical cavities, respectively [7,11,[19][20][21]. The parallel field superposition results in lower resonance frequencies and the antiparallel fields shows the opposite behavior with higher coupled microwave (mw) resonance frequencies.…”

Section: Introductionmentioning

confidence: 99%

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Dielectric Ceramic EPR Resonators for Low Temperature Spectroscopy at X-band Frequencies

Friedländer

Ovchar²,

Voigt

et al. 2014

Appl Magn Reson

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The performance of new dielectric ceramic resonators (DRs) for continuous wave (cw) X-band electron paramagnetic resonance (EPR) spectroscopy is investigated at room temperature and low temperatures (77, 6 K). The DRs with high dielectric constants of about e r ¼ 80, featuring low residual paramagnetic impurities, have been developed and produced on the basis of barium lanthanide titanates solid solutions with the general formula Ba 6Àx Ln 8þ2x=3 Ti 18 O 54 (Ln = Sm, Nd) that demonstrate at once low dielectric losses in the microwave range (tan d ¼ 7-14 9 10 -4 at 10 GHz) and appropriate temperature stability of the dielectric constant (s e ¼ AE5 ppm/K). They were optimized for samples with small dimensions and can be used in commercial Oxford instruments flow cryostats if the coupling is done via cavity resonators. We found a maximal EPR signal enhancement by a factor up to 74 at 6 K. The increases of quality and filling factors as well as that of the microwave (mw) B 1 -field in the resonator setup are discussed in dependence on temperature. We show that the absolute sensitivity gain must be related to that increase in the mw field and the remaining relative gain of the SNR is Electronic supplementary material The online version of this article (Applied Magnetic Resonanceabout 18 for small samples. The developed DRs have shown a good potential in EPR application as reliable and easy-to-use components allowing research of thin films and in particular small crystalline structures.

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“…This makes the calculation expressible analytically in closed form, unlike the DR, which is surrounded by evanescent fields [25–27]. In addition, there is no mode splitting [18, 19, 21]. The calculation is exact for any aspect ratio of the tube or cavity.…”

Section: Introductionmentioning

confidence: 99%

EPR Uniform Field Signal Enhancement by Dielectric Tubes in Cavities

Hyde

Mett

2017

Appl Magn Reson

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The dielectric tube resonator (DTR) for EPR spectroscopy is introduced. It is defined as a metallic cylindrical TE011 microwave cavity that contains a dielectric tube centered on the axis of the cylinder. Contour plots of dimensions of the metallic cylinder to achieve resonance at 9.5 GHz are shown for quartz, sapphire, and rutile tubes as a function of wall thickness and average radius. These contour plots were developed using analytical equations and confirmed by finite element modeling. They can be used in two ways: design of the metallic cylinder for use at 9.5 GHz that incorporates a readily available tube such as a sapphire tube intended for NMR, or design of a custom procured tube for optimized performance for specific sample-size constraints. The charts extend to the limiting condition where the dielectric fills the tube. However, the structure at this limit is not a dielectric resonator due to the metal wall and does not radiate. In addition, the uniform field (UF) DTR is introduced. Development of the UF resonator starting with a dielectric tube resonator is shown. The diameter of the tube remains constant along the cavity axis, and the diameter of the cylindrical metallic enclosure increases at the ends of the cavity to satisfy the uniform field condition. This structure has advantages over the previously developed UF TE011 resonators: higher resonator efficiency parameter Λ, convenient overall size when using sapphire tubes, and higher quality data for small samples. The DTR and UF DTR structures fill the gap between free space and dielectric resonator limits in a continuous manner.

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Analysis of two stacked cylindrical dielectric resonators in a TE102 microwave cavity for magnetic resonance spectroscopy

Cited by 16 publications

References 55 publications

Single Crystal Electron Paramagnetic Resonance with Dielectric Resonators of Mononuclear Cu²⁺ Ions in a Metal–Organic Framework Containing Cu₂ Paddle Wheel Units

Single Crystal Electron Paramagnetic Resonance with Dielectric Resonators of Mononuclear Cu²⁺ Ions in a Metal–Organic Framework Containing Cu₂ Paddle Wheel Units

Dielectric Ceramic EPR Resonators for Low Temperature Spectroscopy at X-band Frequencies

EPR Uniform Field Signal Enhancement by Dielectric Tubes in Cavities

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Analysis of two stacked cylindrical dielectric resonators in a TE102 microwave cavity for magnetic resonance spectroscopy

Cited by 16 publications

References 55 publications

Single Crystal Electron Paramagnetic Resonance with Dielectric Resonators of Mononuclear Cu2+ Ions in a Metal–Organic Framework Containing Cu2 Paddle Wheel Units

Single Crystal Electron Paramagnetic Resonance with Dielectric Resonators of Mononuclear Cu2+ Ions in a Metal–Organic Framework Containing Cu2 Paddle Wheel Units

Dielectric Ceramic EPR Resonators for Low Temperature Spectroscopy at X-band Frequencies

EPR Uniform Field Signal Enhancement by Dielectric Tubes in Cavities

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Product

Resources

About

Single Crystal Electron Paramagnetic Resonance with Dielectric Resonators of Mononuclear Cu²⁺ Ions in a Metal–Organic Framework Containing Cu₂ Paddle Wheel Units

Single Crystal Electron Paramagnetic Resonance with Dielectric Resonators of Mononuclear Cu²⁺ Ions in a Metal–Organic Framework Containing Cu₂ Paddle Wheel Units