ESR spectroscopy employing YIG-Tuned Oscillator in conjunction with low-quality factor resonators

Electron spin resonance (ESR) is a very useful and robust microwave spectroscopic method with many applications in science and technology. Common microwave sources used in ESR spectroscopy, such as klystrons or Gunn diodes have small bandwidth of ~1GHz (at 10 GHz) and need to be locked on high-Q cavity (Q>;1000) to achieve low phase noise at 100 kHz offset. Here we developed an experimental system with YIG-Tuned Oscillator, which can be used for ESR spectroscopy in the entire range of 8-18GHz and can be locked on relatively low Q resonators (Q>;200). The hysteresis of YIG-Tuned Oscillator does not affects its performance and even at the low Q values one obtains tracking error of the resonator frequency that are ~10-100 kHz.