Scheme 2. Schematic Diagram of the Pulse Sequences Used for the Detection of HP Gas.

(a) In the weakly spin–spin coupled regime, i.e., high field of 1.4 T for detecting H_A and H_B magnetization, and (b) in the strongly spin–spin coupled regime, i.e., low field of 0.0475 T for conversion of singlet spin states into observable magnetization using partial SLIC. Nonobservable singlet spin order and observable magnetization states are used as simplified notations of the overpopulated states of H_A and H_B before and after the SLIC pulse.