Improving B1 field homogeneity in dielectric tube resonators for EPR spectroscopy via controlled shaping of the dielectric insert

• Published in: Journal of magnetic resonance (1997) 2020-02, Vol.311, p.106685-106685, Article 106685
• Main Authors: Syryamina, Victoria N., Matveeva, Anna G., Vasiliev, Yan V., Savitsky, Anton, Grishin, Yuri A.
• Format: Article
• Language: English
• Subjects: Dielectric resonator; EPR; Homogeneity of microwave magnetic field amplitude
• ISSN: 1090-7807; 1096-0856
• DOI: 10.1016/j.jmr.2020.106685

[Display omitted] •The approach for manipulating B1 field distribution in dielectric tube resonators for EPR spectroscopy is proposed.•The sensitivities for CW and pulse EPR measurements in shaped and standard inserts are compared.•The benefit of the shaped dielectric insert for spin-counting DEER measurements for long samples is demonstrated. We propose an approach for improving the homogeneity of microwave magnetic field amplitude in a dielectric tube resonator for electron paramagnetic resonance spectroscopy at X-band. The improvement is achieved by “shaping” (controllable variation of the outer diameter of a dielectric insert along its axial direction). Various shaping scenarios based on the principle of discrete solenoids and electromagnetic calculations have been considered. The dielectric insert having the most promising shape was manufactured from a bismuth germanate single crystal. The shaped insert increases the area at B1 > 0.9 B1max from 5.06 to 7.36 mm. Higher sensitivity and lower likelihood of quantitative errors have been achieved in pulse EPR experiments for “long” samples (whose length was comparable to that of the dielectric insert) in a shaped dielectric insert.