## 3 Results
### Evaluation of the Chemical Shift Derived from the JCS  
The chemical shifts in the LF strong coupling regime are primarily disregarded when performing chemical analysis since \({}^{1}\)H spectra are typically investigated. To date, the only measured chemical shifts at the earth's field (50 \(\upmu\)T) have been obtained for hyperpolarized \({}^{129}\)Xe, and there are no reports where chemical shifts have been measured in strongly coupled systems [57; 58]. Assuming a 2 kHz Larmor frequency, the entire 10 ppm \({}^{1}\)H chemical shift range falls within 20 mHz, which is smaller than the natural linewidths obtained at these magnetic fields. However, nuclei with larger chemical shift ranges, such as \({}^{19}\)F, \({}^{31}\)P, and \({}^{207}\)Pb, should show observable chemical shifts. This is due in part to the larger chemical shift range, as well as the lower Larmor frequencies. Fluorobenzene have \({}^{19}\)F chemical shifts ranging from \(-\)110 to \(-\)163.1 ppm (Table 3), which is substantially larger than the chemical shift of the reference compound, CFCl\({}_{3}\). Using IUPAC convention, the magnetic field was calibrated by setting the tetramethylsilane (TMS) resonance to the \({}^{1}\)H Larmor frequency [59]. The \({}^{19}\)F of the reference, CFCl\({}_{3}\), was then set to 94.094011% of the TMS resonance [59]. Therefore, the chemical shift of both nuclei was referenced to \(\delta_{\text{iso}}\) = 0 ppm. The effects of including chemical shift are shown in Table 3 and illustrated in Figure 7 for a (1:1) mixture of hexafluorobenzene and benzene. Visually, it is evident that there is a chemical shift difference in the \({}^{19}\)F spectrum. The general trend observed, when incorporating the \({}^{19}\)F chemical shift in simulations, is that as the amount of \({}^{19}\)F increases in the  
Figure 6: Comparison between experimentally determined and _ab initio_ calculated \({}^{4}\)J\({}_{\text{HH}}\) (**a**) and \({}^{5}\)J\({}_{\text{HF}}\) (**b**). The symbols correspond to different compounds (\(\bullet\) monofluuorobenzene, + 1,2 difluorobenzene, \(\times\) 1,3-difluorobenzene, \(\Diamond\) for 1,4 difluorobenzene, \(\blacktriangle\) 1,2,4- trifluorobenzene, \(\blacklozenge\) for pentafluorobenzene). A linear dependence was observed for both datasets, which indicates that the opposite relative sign obtained from _ab initio_ calculations is due to the known scaling issues for these calculations. Therefore, when calculated or experimental _J_-couplings are near zero, a sign error may result; however, this is remedied by applying a linear correction factor. molecule, the impact of the chemical shift has a more pronounced effect on the R-factor, and this is shown in the spectral behavior of monofluorobenzene versus pentafluorobenzene. The relative amount of F in monofluorobenzene was 1/6 of the total peak area, and the \(R\)-factor was dominated by the \({}^{1}\)H portion of the spectrum, which is largely independent of the chemical shift, since it falls well within the linewidth. On the other hand, the pentafluorobenzene spectrum was \(\approx\)5/6 \({}^{19}\)F, and when these peaks are not well simulated, the \(R\)-factor increased. Comparing the simulations to experimental data, it is clear that the chemical shift cannot always be neglected in the strong heteronuclear \(J\)-coupling regime. Thus, the JCS simulations of the fluorobenzene compounds accurately reflect the experimental data only if all the NMR observables of Larmor frequency, \(J\)-couplings (both heteronuclear and homonuclear), and chemical shifts are taken into account. This further demonstrates that, since these parameters are all measurable from the JCS spectrum, they can be used for chemical analysis.