Fig. 1.

Chemical structure, photocycle, and time dependence of the magnetic field effect (MFE) of CPF. a Structure of the molecular CPF triad. b Simplified photoscheme including all processes of relevance for this study. For simplicity, the secondary radical pair C^•+-P-F^•− is shown as created in a pure singlet state. For more detailed photochemical information, refer to refs. ^40,41. c Transient absorption subtraction signal ΔΔA of the radical pair, probed at 980 nm, obtained upon application of a magnetic field of B₀ = 100 μT. The dotted lines in red, green, and blue indicate delay times of 0.08, 0.28, and 0.71 μs after laser excitation, respectively. d Magnetic field dependence of the MFE averaged for a time window of 20 ns centred around the indicated delay times. The dotted black line indicates the field position of 100 μT and the field region approximately corresponding to the low field region is highlighted in grey