To check the applicability of the OPTIANS in correlation experiments, we performed two-dimensional (2D) 19 F- 7 Li heteronuclear correlation (HETCOR) experiments using CP and OPTIANS. The comparison is shown in Figure ) with 19 F and 7 Li projections in Figure (C) and Figure (D), respectively. The 2D spectrum has single peak as expected for the Na3Li3Al2F12 sample. The 7 Li projection signal is ~50% greater than that of the CP. Though we used the optimal experimental parameters, i.e., t ()*+,(+ = 400 µs for CP and 1.3 ms for the OPTIANS, yet the difference in the intensities is significantly larger than the earlier observed value of 11%. Though we don't have an exact explanation for this trend, but the loss of efficiency could be ascribed to experimental imperfections during the 2D experiment and the dephasing during the evolution period that makes the spin-locking less efficient. The impact of variation in the offset frequency and power levels are shown in Figures S8 and S9 in the SI, in which the peak intensities of the 1D 19 F- 7 Li spectra are plotted with varying offsets and RF amplitudes. The OPTIANS is offset selective as predicted in the numerical simulations shown in Figure . Fig. . 2D 19 F- 7 Li correlation experiments and their projections. 19 F- 7 Li HETCOR experiment with (A) OPTIANS and (B) CPMAS used as polarization transfer block. The projections of 7 Li and 19 F are presented in (C) and (D), respectively. For each case the optimal contact times and power levels are used. In both the cases, 128 FIDs are acquired in indirect dimension with 4 scans and relaxation delay of 5 s such that the total experimental time is 43 min.