Dresden 2011 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 11: Poster: New Instruments and Methods

CPP 11.18: Poster

Montag, 14. März 2011, 17:30–19:30, P2

NMR Signal Averaging in 62 Tesla Pulsed Fields — •Benno Meier¹, Sebastian Greiser¹, Jürgen Haase¹, Thomas Herrmannsdörfer², Frederik Wolff-Fabris², and Joachim Wosnitza² — ¹University of Leipzig, Faculty of Physics and Earth Science, Linnéstrasse 5, 04103 Leipzig, Germany — ²Hochfeld-Magnetlabor Dresden, Forschungszentrum Dresden-Rossendorf, 01328 Dresden, Germany

Nuclear Magnetic Resonance (NMR) experiments at up to 62 Tesla in pulsed high magnetic fields at the Hochfeldlabor Dresden-Rossendorf are reported. The time dependence of the magnetic field is investigated by observing various free induction decays (FIDs) in the vicinity of the maximum of the pulse. By analyzing each FID’s initial phase and its evolution with time the magnetic field’s time dependence can be determined with high precision. Assuming a cubic dependence on time near the field maximum its confidence is found to be better than ± 0.03 ppm at low fields and ± 0.8 ppm near 62 Tesla. The obtained time dependence of the field can be used to demodulate and phase correct all FIDs so that they appear phase locked to each other. As a consequence signal averaging is possible. The increase in signal-to-noise is found to be close to that expected theoretically. This shows that the intrinsic time dependence of these pulsed field can be removed so that the NMR signals appear to be taken at rather stable static field. This opens up the possibility of performing precise shift measurements and signal averaging also of unknown, weak signals if a reference signal is measured during the same field pulse with a double-resonance probe.