1.1-GHz continuous-wave EPR spectroscopy with a frequency modulation method.
Continuous-wave EPR spectroscopy using a frequency modulation (FM) scheme was developed. An electronically tunable resonator and an automatic tuning control (ATC) system were used. Using the FM scheme instead of magnetic field modulation, we detected EPR absorption at the first derivative mode. We used a microwave frequency of 1.1 GHz in the present experiment. Similar signal-to-noise ratios were obtained with conventional field modulation and the FM method, and a low-quality factor EPR resonator was not necessary to suppress the significant microwave reflection from the resonator. The FM method with a tunable resonator may be an alternative solution to achieving phase-sensitive detection, when the side-effects of magnetic field modulation, such as microphonic noise and mechanical vibration, are detrimental for EPR detection.
Hirata
Hiroshi
H
Department of Electrical Engineering, Yamagata University, Yonezawa 992-8510, Japan. hhirata@yz.yamagata-u.ac.jp
Ueda
Mitsuru
M
Ono
Mitsuhiro
M
Shimoyama
Yuhei
Y