Fig. 6: Evolution of the 1H polarization \((P({S}_{Z}^{4}))\) in the target for different exchange rates K1 = K2 = 6.12–4800 s−1 during PHIP-X.
From: Nuclear spin polarization of lactic acid via exchange of parahydrogen-polarized protons

A maximum target polarization was found at K1 = K2 = 200 s−1 with a monotonic decrease for smaller (a) and larger (b) rates. Note that MFC was initiated at 2400 ms and the dashed lines indicate the transitions between the magnetic fields.