Enhanced accuracy of the microwave field strength measurement in a CW-EPR by pulsed modulation technique

• Published in: Journal of magnetic resonance (1997) Vol. 287; pp. 123 - 127
• Main Authors: Rakvin, B., Carić, D., Kveder, M.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.02.2018
• Subjects: Amplitude modulation EPR; Bloch-Siegert shift; EPR spectroscopy; Microwave field strength; Modulation spectrum; Modulation spectrum; Amplitude modulation EPR; Microwave field strength; EPR spectroscopy; Bloch-Siegert shift
• ISSN: 1090-7807; 1096-0856
• DOI: 10.1016/j.jmr.2018.01.006

[Display omitted] •EPR modulation spectrum was used for measuring microwave magnetic field strength, B1, in CW-EPR experiment.•Bloch-Siegert-like shift is included in simulation of AM-CW-EPR modulation spectra.•Evaluation of B1 value in the presence of microwave saturation effects. The microwave magnetic field strength, B1, in the cavity of a conventional continuous wave electron paramagnetic resonance, CW-EPR, spectrometer was measured by employing modulation sidebands, MS, in the EPR spectrum. MS spectrum in CW-EPR is produced by applying the modulation frequency, ωrf, which exceeds the linewidth, δB, given in frequency units. An amplitude-modulated CW-EPR, AM-CW-EPR, was selected as detection method. Theoretical description of AM-CW-EPR spectrum was modified by adding Bloch-Siegert-like shift obtained by taking into account the cumulative effect of the non-resonant interactions between the driving fields and the spin system. This approach enables to enhance the precision of B1 measurement. In order to increase the sensitivity of the method when saturation effects, due to higher intensity of B1, decrease the resolution of AM-CW-EPR spectrum, detection at the second harmonic of CW-EPR has been employed.