Figure 3. Broadband cavity-enhanced absorption spectra.

(a) BBCEAS response (ΔΔA_r) of DmCry (60 μM in 20% v/v glycerol) as a function of the probe wavelength and the strength of the applied magnetic field. These effects correspond to changes in absorbance on the order of 10⁻⁶ (the subscript r indicates that the BBCEAS response has not been corrected for the cavity enhancement factor, see ref. 22). (b) Magnetic response profile determined by averaging over the wavelength region (500–530 nm) in which the long lived radicals absorb. The error bars represent one standard error of the mean. A B_1/2 value of 4.5 ± 0.9 mT was determined from a Lorentzian fit to the data (red). (c) BBCEAS response of a 30 μM DmCry solution illustrating the commensurate (positive) magnetic field effect in the ground-state bleaching region (λ < 500 nm). All BBCEAS experiments were performed at 278 K.