Dresden 2017 – wissenschaftliches Programm
CPP 37.7: Vortrag
Mittwoch, 22. März 2017, 12:15–12:30, ZEU 255
1H NMR at Larmor frequencies down to 3 Hz by means of Field-Cycling techniques — •Benjamin Kresse1, Manuel Becher1, Alexei F. Privalov1, Marius Hofmann2, Ernst A. Rössler2, Michael Vogel1, and Franz Fujara1 — 1Institut für Festkörperphysik, TU Darmstadt, Hochschulstr. 6, 64289 Darmstadt, Germany — 2Experimentalphysik II, Universität Bayreuth, 95440 Bayreuth, Germany
Field-Cycling (FC) NMR traces spectral densities of molecular or ionic motions by measuring the spin-lattice relaxation dispersion in a broad range of Larmor frequencies. By rapidly switching the magnetic field from a high polarization field down to a small evolution field the relaxation process can be tracked in ultra low magnetic fields by switching up to a high detection field for signal acquisition. This contribution briefly deals with the technical part of our home built FC relaxometer and focuses on experiments at ultra low Larmor frequencies down to about 3 Hz demonstrating the performance of FC NMR. Several low field experiments are presented: Larmor precession about tilted evolution fields, simultaneous measurements of the Larmor frequency and the spin-lattice relaxation [B. Kresse, A. F. Privalov, A. Herrmann, M. Hofmann, E. A. Rössler, F. Fujara; Solid State NMR 59-60 (2014) 45-47.] as well as the irradiation of oscillating transversal magnetic field pulses as a novel method for field calibration in low field FC NMR. The potential of low field FC is exemplified by the 1H relaxation dispersion of water at low frequencies stemming from the slow proton exchange process.