Protocol (b) in figure employs the rotating-field STORM technique for the polarization transfer. After bubbling with para-enriched H 2 , the transverse rotating STORM field was applied for a duration τ T in the presence of a longitudinal 6 µT bias field. The amplitude of the rotating STORM field was B STORM = 3.9 µT. The rotation frequency of the STORM field was ω STORM /2π =72.5 Hz. As discussed in the supplementary material, this choice of field parameters decouples the proton spins from the deuterium spins during the transfer step. Figure shows the resulting 13 C spectrum for an optimal STORM duration of τ T =100 ms. The final 13 C polarization was estimated to be p =1.70%±0.22%, which is significantly higher than that for protocol (a). Since the bubbling protocols are identical in procedures (a) and (b), we attribute the increase in the 13 C polarization level to the robustness of the STORM pulse with respect to interference from fast deuterium relaxation.