Scheme 2.

a) Diagram of the pairwise addition of pH₂ to propylene over the Rh/TiO₂ catalyst. b) the sequential steps of the signal acquisition method using the 0.0475 T setup for the measurement of HP propane T_LLS (achieved by varying the relaxation delay τ_R), optimization of the chamber-refill time τ_CR, and optimization of SLIC transformation (varying RF amplitude, power, and frequency offset). c) Corresponding pulse sequence used for HP propane T₁ measurements using 90° RF pulse (to create z-magnetization) after SLIC irradiation followed by a small angle (α) RF pulse; note the SLIC pulse and chamber refill are performed once in the sequence shown in c) versus multiple refills employed in sequence shown in b). d) Diagram of the pairwise addition of pH₂ to propylene-d₆ over the Rh/TiO₂ catalyst. e) Pulse sequence used for the measurement of HP propane-d₆ T_LLS. Note the pH₂ symmetry breaking is achieved by the chemical reaction, with nascent protons H_A and H_B placed in methylene and methyl chemical groups in a) and d).