efficiency is highly dependent on the offset value. The optimal performance is observed only for on-resonance conditions. As mentioned in materials and methods, during OC optimization, the isotropic chemical shifts for all three 19 F isotopes were calibrated to 0 ppm, rendering the OPTIANS highly susceptible to offset variations. Though further analysis of the polarization transfer mechanism may lead to a method that can expand the frequency profile of this pulse sequence, the offset selectivity can be used to probe the specific correlations avoiding the cluttering in the spectra. Li polarization transfer curves recorded using CP (blue) and OPTIANS (red). The time steps were 100 𝜇𝑠 in CP and ~200 𝜇s in case of OPTIANS. Red and blue dotted lines represent the optimal contact times for OPTIANS (1.3 ms) and CPMAS (400 𝜇s), respectively. Comparison of 7 Li MAS NMR signal recorded using CPMAS (blue) and OPTIANS (red) with (B) optimal contact time (dotted lines) and (C) with ~1 ms of contact time (solid lines). The peak areas of the 7 Li signal, normalized to most intense peak in the CP polarization transfer curve, are plotted with the CP and OPTIANS contact time (t ()*+,(+ ) in Figure (A). The CP polarization transfer curve shows a rapid decrease after the peak at 400 𝜇s, which is a manifestation of a short rotating frame relaxation time constant, 𝑇 .3 and complex spin-dynamics due to the presence of large 19 F CSA and 7 Li QC. The 𝑇 .3 effect is less pronounced in OPTIANS due to the rapidly oscillating amplitudes and phases as this method doesn't rely on spin-locking for the polarization transfer. The CP results into negative peak intensity for t ()*+,(+ > 1.5 ms due to the interaction between RF and CSA, as verified using numerical simulations shown in Figure , and discussed earlier. The OPTIANS shows 11% higher efficiency compared to the optimal CP efficiency. The slower polarization rate in the OPTIANS is a consequence of higher order recoupling as indicated and discussed in the simulations results. Moreover, it clearly shows more robustness towards 𝑇 .3 effect as highlighted in the comparison of the 1D at longer contact-time cause by the 𝑇 .3 and complex spin dynamics, forbids the application of CP to weakly coupled quadrupolar -spin-1/2 pairs. Note that polarization transfer at longer distances, 3-4 Å (680 kHz < 𝜈 44 $&' < 1630 kHz) for 19 F-7 Li, are critical to gain insight into the local structure and dynamics. In simulations Figure , the OPTIANS showed transient oscillations that are not observed in the experimental polarization transfer curves. The damping of oscillations is ascribed to the presence of distribution of 19 F-19 F and 19 F- 7 Li dipolar couplings in the sample, as shown in Figure .