Extended Data Fig. 1: EPR spectral lineshapes.
(a) Qualitative simulations of the ESE intensity patterns observed for compounds 2 and 4. The full spectra (in purple) were generated by summing individual hyperfine components – the eight colored curves above each summed spectrum, labeled according to the associated nuclear projection, mI. The asymmetric lineshapes of the individual components are dictated by the \(\overleftrightarrow g\)-tensor anisotropy and the spacing by the hyperfine and nuclear quadrupole interactions. These simulations capture the main features observed in the experimental spectra, particularly the staircase increase in intensity on the low-field side of the spectrum for 2. The pink oval highlights the region of the spectrum shown in (b). (b) Zoomed region of the experimental spectrum of 4, from Fig. 3c, showing the feature that is very sensitive to the NQI. Superimposed are simulations for different values of Qzz, from which the optimum value of 100 ± 20 MHz is deduced (Table 1). We note that the qualitative simulations in (a) do not explicitly take into account the NQI, whereas the exact simulations in (b) do; for further details, see Supplementary Information Section 3.
