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BP: Fachverband Biologische Physik

BP 26: Posters II

BP 26.15: Poster

Thursday, February 28, 2008, 17:00–19:30, Poster A

Biological NMR Spectroscopy: Hyperpolarization at Variable Field — •Sergey Korchak, Konstantin Ivanov, Talea Köchling, Alexandra Yurkovskaya, and Hans-Martin Vieth — Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, D-14195 Berlin, Germany

For optimization of nuclear spin hyperpolarization and its transfer to target spins of choice field-cycling schemes have been devised that make use of scalar spin-spin interaction J in the strong coupling regime. A field-cycling unit is described shuttling the NMR probe along the bore axis of the spectrometer cryomagnet and allowing field variation between 1 uT and 7 T combined with high resolution detection. By incrementing spin evolution times an oscillatory exchange of polarization between spins is observable allowing efficient manipulation of polarization flow. We studied coherent transfer of chemically induced dynamic nuclear polarization (CIDNP) in the amino acids histidine, tyrosine and tryptophan and observed well-pronounced quantum beats in their transfer kinetics indicating the coherent nature of the process. In the field dependence of the CIDNP transfer efficiency features such as peaks and dips were found corresponding to anti-crossings of the nuclear spin levels in the molecule. In experiments performed at very low field (about 1 uT) where hetero-nuclei become strongly coupled coherent CIDNP transfer between protons and fluorine atoms was found. An adequate theoretical approach to the phenomena studied was developed. This work was supported by the EU (Bio-DNP grant # 011721 and IFF # 22008) and INTAS (grant # 05-1000008-807).