Figure 6.

Simplified FAD-Trp radical pair with a dipolar coupling, D = −407 μT. (a) Action-spectrum histogram (bin width, 1 MHz). This plot is more structured than the histogram in Fig. 5a because of the reduced number of nuclear spins. (b) The anisotropic singlet yield, Φ_S(θ), in the presence of 1.4 and 2.8 MHz single-frequency fields and a 0–10 MHz broadband field. The 1.4 MHz (blue) and 2.8 MHz (red) traces are almost indistinguishable. The following hyperfine interactions were included: in FAD^•−, N5, N10, H6, and H8; and in TrpH^•+, N1, H1, H2, and H4. The narrow spike at θ = 90° (Fig. 5b) has been abolished by the dipolar interaction.