Selective quenching of magnetic field effect for radical ion pairs with widely different hyperfine couplings

The effect of selective quenching of magnetic field effect by a non-selective chemical reaction due to different rates of spin evolution in radical pairs is demonstrated. In the case of several parallel radical pairs a more rapid disappearance of magnetic signal from a pair does not mean a faster chemical decay of the underlying pair, if the hyperfine couplings in the pairs are significantly different. The presence of two signals with different sensitivity to quencher in the spectrum gives the effect of internal standard and helps to extract quantitative information from the intensities rather than widths of signals in spectra.