Figure 5.

The schematic of ROS generation. Flavin semiquinone (FADH^•) and superoxide (O₂ ^•-) spin-correlated radical pair (top). The radical pairs undergo intersystem crossing (ISC) between singlet (S) and triplet states (T_-1,0,1) at rates (kISC) determined by electron-nuclear hyperfine and Zeeman interactions (middle). An applied RF oscillating magnetic field tuned at Zeeman resonance (1.4 MHz at 50 μT magnetic field), modifies kISC (bottom) and ultimately affects the relative amount of singlet (H₂O₂) and triplet (O₂ ^•-) reaction products. Resonance effect on ROS product yields is a key manifestation of quantum biology.