Fields of Research: PHIP

Parahydrogen Induced Polarization (PHIP)

The difference between ordinary NMR spectra and PHIP-NMR, illustrated for an AX spin system:

1. Energy levels and simulated NMR spectrum of a conventional AX spin system
2. Energy levels and simulated NMR spectrum of hydrogenation with parahydrogen 

The pairwise addition of enriched parahydrogen to an organic substrate or a metal complex leads to polarization effects in NMR spectroscopy. "Pairwise" means, that spin correlation is  maintained between the two transferred protons.

The polarization signals originate from a selective population of the product's nuclear spin levels that contain some singlet character.

For a simple AX-spin system as it is shown above the spin functions ab and ba are overpopulated relative to a normal Boltzmann distribution. As a consequence, polarization signals are enhanced by some orders of magnitude and arise in absorption and emission. The enhancement of the sensitivity of the NMR detection method can reach values of a few powers of ten, but typically ranges around a factor of a few thousand. The method is extremely sensitive for the detection of short-lived intermediates and reaction products in small concentrations.

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