Comparison of CW and rapid-scan spectra of BMPO-OOH in solution with a O2⋅− production rate of 0.1 μM/min, recorded 10 min after mixing reagents. The O2⋅− was produced by a hypoxanthine/xanthine oxidase mixture. The concentration of BMPO-OOH is ∼0.3 μM. (A) CW spectrum obtained with 55 G sweep width, 0.75 G modulation amplitude, single 30 s scan, 15 ms conversion time, 10 ms time constant, and 20 mW (B1 = 170 mG) microwave power. (B) Deconvolved rapid-scan spectrum obtained with 55 G scan width, 51 kHz scan frequency, and 53 mW (B1 = 250 mG) microwave power. Segments consisting of 12 sinusoidal cycles were averaged 100 k times, with a total data acquisition time of ∼30 s.