Dresden 2009 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 15: POSTERS Dynamics and Diffusion

CPP 15.6: Poster

Dienstag, 24. März 2009, 14:00–16:30, P3

Para-hydrogen induced nuclear spin polarization at variable magnetic field — •Sergey Korchak¹, Konstantin Ivanov², Alexandra Yurkovskaya^1,2, and Hans-Martin Vieth¹ — ¹Fachbereich Physik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin — ²International Tomography Center, Institutskaya 3a, Novosibirsk, Russia

A way of boosting the sensitivity of NMR is exploiting hyperpolarization resulting from non-thermal population of the spin energy levels. A very efficient method is enriching the para-spin isomer of H₂ (PHIP) and subsequent transferring the polarization to target spins of choice. This has been applied in magnetic resonance imaging in biological studies. Both the PHIP effect and the polarization transfer vary strongly with an external magnetic field B. We will report a detailed experimental and theoretical study of this magnetic field dependence. As a model system polarized ethylbenzene formed by catalytical attachment of the para-H₂ molecule to styrene was measured at fields ranging from 0.1mT to 7T by use of a fast field-cycling technique. Theoretical simulations of the polarization pattern as a function of B assuming scalar spin-spin coupling to be responsible for the change reproduce the experimental data for this 5-spin system. Polarization transfer across several bonds from the primarily polarized aliphatic protons to the aromatic moiety of ethylbenzene was also observed. The optimal conditions for forming polarization and manipulating its transfer as well as the influence of spin-lattice relaxation will be discussed.