Fig. 8: 1H and 13C polarization of the fixed proton and carbon in the target molecule during a PHIP-X experiment.
From: Nuclear spin polarization of lactic acid via exchange of parahydrogen-polarized protons
a For the first 2400 ms, the system evolved at BPol0 = 90 mT, and 1H polarization was built up (\(P\left({S}_{Z}^{4}\right)\)). When the system was dropped to BPol1 = 5 µT (in 15 ms), the polarization started to oscillate between \(P\left({S}_{Z}^{4}\right)\) and \(P\left({S}_{Z}^{3}\right)\). When the field was increased (in 15 ms) to B0 = 1 T, the oscillations stopped, and the latest polarization of the oscillation was preserved. The largest amplitude and the lowest frequency were observed (b) for BPol1 < 100 nT. Note that the oscillations are modulated also by lower frequencies (5 Hz or 3 Hz) time, so that significant 13C polarization can be obtained by increasing the field to B0 at the right time.
