PHIP sequences and dipolar fields II—Dual-channel control

Parahydrogen induced polarisation (PHIP) achieves efficient hyperpolarisation of nuclear spins at room temperature with the transfer of the singlet order of parahydrogen to target molecules through catalytic hydrogenation reactions and subsequent coherent control of the spin dynamics. However, in realistic conditions B0/B1 inhomogeneities, imperfect chemical equivalence and dipolar fields arising from the magnetisation of the sample can degrade polarisation transfer efficiency significantly. In this work (part II), we extend the theoretical framework of part I (Korzeczek et al., 2026) to dual-channel sequences which drive both the carbon-13 (/heteronuclear) and hydrogen spins. This allows for strong robustness properties at increased transfer rates and an increased robustness to chemical shifts between the parahydrogen spins.