Configuration for Bruker EMX Micro EPR spectrometer: Frequency: 9.83 GHz; Power: 3.17 mW; Modulation frequency: 100 kHz; Modulation amplitude: 1 G; Time constant: 40.96 msec; Number of scans: 5; Sweep width: 100 G (for DMPO and PBN adducts, TEMPO) or 170 G (for DEPMPO adducts)