Continuous-wave EPR measurements were performed by using a Bruker E500 ElexSys EPR spectrometer and ER4123SHQE X-band cavity resonator as described.14 (link) EPR acquisition parameters: Microwave frequency, 9.45 GHz; microwave power, 0.2 mW; magnetic field modulation, 0.2 mT; modulation frequency, 100 kHz; acquisition number, 4–8 spectra were averaged at each T value.